diff --git a/src/coreclr/debug/daccess/enummem.cpp b/src/coreclr/debug/daccess/enummem.cpp
index b8b505744ad995..d771b06dcf5b57 100644
--- a/src/coreclr/debug/daccess/enummem.cpp
+++ b/src/coreclr/debug/daccess/enummem.cpp
@@ -2050,7 +2050,7 @@ ClrDataAccess::EnumMemoryRegions(IN ICLRDataEnumMemoryRegionsCallback* callback,
     fprintf(fp, "Total = %g msec\n"
                "ReadVirtual = %g msec\n"
                "StackWalk = %g msec; Find: %g msec\n"
-               "Find = %g msec; Hash = %g msec; Calls = %I64u; Hits = %I64u; Not found = %I64u\n\n=====\n",
+               "Find = %g msec; Hash = %g msec; Calls = %llu; Hits = %llu; Not found = %llu\n\n=====\n",
                (float) (1000*g_nTotalTime/nClockFrequency.QuadPart),
                (float) (1000*g_nReadVirtualTotalTime/nClockFrequency.QuadPart),
                (float) (1000*g_nStackTotalTime/nClockFrequency.QuadPart), (float) (1000*g_nFindStackTotalTime/nClockFrequency.QuadPart),
diff --git a/src/coreclr/debug/di/process.cpp b/src/coreclr/debug/di/process.cpp
index 51f3e6317bd925..206a5df26c1edc 100644
--- a/src/coreclr/debug/di/process.cpp
+++ b/src/coreclr/debug/di/process.cpp
@@ -12296,7 +12296,7 @@ Reaction CordbProcess::Triage1stChanceNonSpecial(CordbUnmanagedThread * pUnmanag
                       (addrType == IDacDbiInterface::kAddressRuntimeManagedCode) ||
                       (addrType == IDacDbiInterface::kAddressRuntimeUnmanagedCode));
 
-    STRESS_LOG2(LF_CORDB, LL_INFO1000, "W32ET::W32EL: IsCorCode(0x%I64p)=%d\n", address, fIsCorCode);
+    STRESS_LOG2(LF_CORDB, LL_INFO1000, "W32ET::W32EL: IsCorCode(0x%p)=%d\n", address, fIsCorCode);
 
 
     if (fIsCorCode)
diff --git a/src/coreclr/gc/handletable.cpp b/src/coreclr/gc/handletable.cpp
index 0af5d3ed9f4641..5979f9646499ce 100644
--- a/src/coreclr/gc/handletable.cpp
+++ b/src/coreclr/gc/handletable.cpp
@@ -1120,14 +1120,14 @@ void DEBUG_LogScanningStatistics(HandleTable *pTable, uint32_t level)
             // dump the generation number and the number of blocks scanned
             LOG((LF_GC, level,     "--------------------------------------------------------------\n"));
             LOG((LF_GC, level,     "    Condemned Generation      = %d\n", i));
-            LOG((LF_GC, level,     "    Blocks Scanned            = %I64u\n", totalBlocksScanned));
+            LOG((LF_GC, level,     "    Blocks Scanned            = %llu\n", totalBlocksScanned));
 
             // if we scanned any blocks in this generation then dump some interesting numbers
             if (totalBlocksScanned)
             {
-                LOG((LF_GC, level, "    Blocks Examined           = %I64u\n", pTable->_DEBUG_TotalBlocksScannedNonTrivially[i]));
-                LOG((LF_GC, level, "    Slots Scanned             = %I64u\n", pTable->_DEBUG_TotalHandleSlotsScanned       [i]));
-                LOG((LF_GC, level, "    Handles Scanned           = %I64u\n", pTable->_DEBUG_TotalHandlesActuallyScanned   [i]));
+                LOG((LF_GC, level, "    Blocks Examined           = %llu\n", pTable->_DEBUG_TotalBlocksScannedNonTrivially[i]));
+                LOG((LF_GC, level, "    Slots Scanned             = %llu\n", pTable->_DEBUG_TotalHandleSlotsScanned       [i]));
+                LOG((LF_GC, level, "    Handles Scanned           = %llu\n", pTable->_DEBUG_TotalHandlesActuallyScanned   [i]));
 
                 double blocksScanned  = (double) totalBlocksScanned;
                 double blocksExamined = (double) pTable->_DEBUG_TotalBlocksScannedNonTrivially[i];
diff --git a/src/coreclr/gcinfo/gcinfoencoder.cpp b/src/coreclr/gcinfo/gcinfoencoder.cpp
index d4596334bd3dc4..58ce1b5bcf7f17 100644
--- a/src/coreclr/gcinfo/gcinfoencoder.cpp
+++ b/src/coreclr/gcinfo/gcinfoencoder.cpp
@@ -384,45 +384,45 @@ void GcInfoSize::Log(DWORD level, const char * header)
         LogSpew(LF_GCINFO, level, header);
 
         LogSpew(LF_GCINFO, level, "---COUNTS---\n");
-        LogSpew(LF_GCINFO, level, "NumMethods: %Iu\n", NumMethods);
-        LogSpew(LF_GCINFO, level, "NumCallSites: %Iu\n", NumCallSites);
-        LogSpew(LF_GCINFO, level, "NumRanges: %Iu\n", NumRanges);
-        LogSpew(LF_GCINFO, level, "NumRegs: %Iu\n", NumRegs);
-        LogSpew(LF_GCINFO, level, "NumStack: %Iu\n", NumStack);
-        LogSpew(LF_GCINFO, level, "NumUntracked: %Iu\n", NumUntracked);
-        LogSpew(LF_GCINFO, level, "NumTransitions: %Iu\n", NumTransitions);
-        LogSpew(LF_GCINFO, level, "SizeOfCode: %Iu\n", SizeOfCode);
-        LogSpew(LF_GCINFO, level, "EncInfoSize: %Iu\n", EncInfoSize);
+        LogSpew(LF_GCINFO, level, "NumMethods: %zu\n", NumMethods);
+        LogSpew(LF_GCINFO, level, "NumCallSites: %zu\n", NumCallSites);
+        LogSpew(LF_GCINFO, level, "NumRanges: %zu\n", NumRanges);
+        LogSpew(LF_GCINFO, level, "NumRegs: %zu\n", NumRegs);
+        LogSpew(LF_GCINFO, level, "NumStack: %zu\n", NumStack);
+        LogSpew(LF_GCINFO, level, "NumUntracked: %zu\n", NumUntracked);
+        LogSpew(LF_GCINFO, level, "NumTransitions: %zu\n", NumTransitions);
+        LogSpew(LF_GCINFO, level, "SizeOfCode: %zu\n", SizeOfCode);
+        LogSpew(LF_GCINFO, level, "EncInfoSize: %zu\n", EncInfoSize);
 
         LogSpew(LF_GCINFO, level, "---SIZES(bits)---\n");
-        LogSpew(LF_GCINFO, level, "Total: %Iu\n", TotalSize);
-        LogSpew(LF_GCINFO, level, "UntrackedSlot: %Iu\n", UntrackedSlotSize);
-        LogSpew(LF_GCINFO, level, "NumUntracked: %Iu\n", NumUntrackedSize);
-        LogSpew(LF_GCINFO, level, "Flags: %Iu\n", FlagsSize);
-        LogSpew(LF_GCINFO, level, "CodeLength: %Iu\n", CodeLengthSize);
-        LogSpew(LF_GCINFO, level, "Prolog/Epilog: %Iu\n", ProEpilogSize);
-        LogSpew(LF_GCINFO, level, "SecObj: %Iu\n", SecObjSize);
-        LogSpew(LF_GCINFO, level, "GsCookie: %Iu\n", GsCookieSize);
-        LogSpew(LF_GCINFO, level, "PspSym: %Iu\n", PspSymSize);
-        LogSpew(LF_GCINFO, level, "GenericsCtx: %Iu\n", GenericsCtxSize);
-        LogSpew(LF_GCINFO, level, "StackBase: %Iu\n", StackBaseSize);
-        LogSpew(LF_GCINFO, level, "FixedArea: %Iu\n", FixedAreaSize);
-        LogSpew(LF_GCINFO, level, "ReversePInvokeFrame: %Iu\n", ReversePInvokeFrameSize);
-        LogSpew(LF_GCINFO, level, "NumCallSites: %Iu\n", NumCallSitesSize);
-        LogSpew(LF_GCINFO, level, "NumRanges: %Iu\n", NumRangesSize);
-        LogSpew(LF_GCINFO, level, "CallSiteOffsets: %Iu\n", CallSitePosSize);
-        LogSpew(LF_GCINFO, level, "Ranges: %Iu\n", RangeSize);
-        LogSpew(LF_GCINFO, level, "NumRegs: %Iu\n", NumRegsSize);
-        LogSpew(LF_GCINFO, level, "NumStack: %Iu\n", NumStackSize);
-        LogSpew(LF_GCINFO, level, "RegSlots: %Iu\n", RegSlotSize);
-        LogSpew(LF_GCINFO, level, "StackSlots: %Iu\n", StackSlotSize);
-        LogSpew(LF_GCINFO, level, "CallSiteStates: %Iu\n", CallSiteStateSize);
-        LogSpew(LF_GCINFO, level, "EhOffsets: %Iu\n", EhPosSize);
-        LogSpew(LF_GCINFO, level, "EhStates: %Iu\n", EhStateSize);
-        LogSpew(LF_GCINFO, level, "ChunkPointers: %Iu\n", ChunkPtrSize);
-        LogSpew(LF_GCINFO, level, "ChunkMasks: %Iu\n", ChunkMaskSize);
-        LogSpew(LF_GCINFO, level, "ChunkFinalStates: %Iu\n", ChunkFinalStateSize);
-        LogSpew(LF_GCINFO, level, "Transitions: %Iu\n", ChunkTransitionSize);
+        LogSpew(LF_GCINFO, level, "Total: %zu\n", TotalSize);
+        LogSpew(LF_GCINFO, level, "UntrackedSlot: %zu\n", UntrackedSlotSize);
+        LogSpew(LF_GCINFO, level, "NumUntracked: %zu\n", NumUntrackedSize);
+        LogSpew(LF_GCINFO, level, "Flags: %zu\n", FlagsSize);
+        LogSpew(LF_GCINFO, level, "CodeLength: %zu\n", CodeLengthSize);
+        LogSpew(LF_GCINFO, level, "Prolog/Epilog: %zu\n", ProEpilogSize);
+        LogSpew(LF_GCINFO, level, "SecObj: %zu\n", SecObjSize);
+        LogSpew(LF_GCINFO, level, "GsCookie: %zu\n", GsCookieSize);
+        LogSpew(LF_GCINFO, level, "PspSym: %zu\n", PspSymSize);
+        LogSpew(LF_GCINFO, level, "GenericsCtx: %zu\n", GenericsCtxSize);
+        LogSpew(LF_GCINFO, level, "StackBase: %zu\n", StackBaseSize);
+        LogSpew(LF_GCINFO, level, "FixedArea: %zu\n", FixedAreaSize);
+        LogSpew(LF_GCINFO, level, "ReversePInvokeFrame: %zu\n", ReversePInvokeFrameSize);
+        LogSpew(LF_GCINFO, level, "NumCallSites: %zu\n", NumCallSitesSize);
+        LogSpew(LF_GCINFO, level, "NumRanges: %zu\n", NumRangesSize);
+        LogSpew(LF_GCINFO, level, "CallSiteOffsets: %zu\n", CallSitePosSize);
+        LogSpew(LF_GCINFO, level, "Ranges: %zu\n", RangeSize);
+        LogSpew(LF_GCINFO, level, "NumRegs: %zu\n", NumRegsSize);
+        LogSpew(LF_GCINFO, level, "NumStack: %zu\n", NumStackSize);
+        LogSpew(LF_GCINFO, level, "RegSlots: %zu\n", RegSlotSize);
+        LogSpew(LF_GCINFO, level, "StackSlots: %zu\n", StackSlotSize);
+        LogSpew(LF_GCINFO, level, "CallSiteStates: %zu\n", CallSiteStateSize);
+        LogSpew(LF_GCINFO, level, "EhOffsets: %zu\n", EhPosSize);
+        LogSpew(LF_GCINFO, level, "EhStates: %zu\n", EhStateSize);
+        LogSpew(LF_GCINFO, level, "ChunkPointers: %zu\n", ChunkPtrSize);
+        LogSpew(LF_GCINFO, level, "ChunkMasks: %zu\n", ChunkMaskSize);
+        LogSpew(LF_GCINFO, level, "ChunkFinalStates: %zu\n", ChunkFinalStateSize);
+        LogSpew(LF_GCINFO, level, "Transitions: %zu\n", ChunkTransitionSize);
     }
 }
 
@@ -2266,8 +2266,8 @@ lExitSuccess:;
         m_CurrentMethodSize.Log(LL_INFO100, "=== PartiallyInterruptible method breakdown ===\r\n");
         g_PiGcInfoSize.Log(LL_INFO10, "=== PartiallyInterruptible global breakdown ===\r\n");
     }
-    LogSpew(LF_GCINFO, LL_INFO10, "Total SlimHeaders: %Iu\n", g_NumSlimHeaders);
-    LogSpew(LF_GCINFO, LL_INFO10, "NumMethods: %Iu\n", g_NumFatHeaders);
+    LogSpew(LF_GCINFO, LL_INFO10, "Total SlimHeaders: %zu\n", g_NumSlimHeaders);
+    LogSpew(LF_GCINFO, LL_INFO10, "NumMethods: %zu\n", g_NumFatHeaders);
 #endif
 }
 
diff --git a/src/coreclr/ilasm/main.cpp b/src/coreclr/ilasm/main.cpp
index 39bf5f11b5d225..f51644ca848974 100644
--- a/src/coreclr/ilasm/main.cpp
+++ b/src/coreclr/ilasm/main.cpp
@@ -173,7 +173,7 @@ extern "C" int _cdecl wmain(int argc, _In_ WCHAR **argv)
 #endif
     {
         printf("\n.NET IL Assembler version " CLR_PRODUCT_VERSION);
-        printf("\n%S\n\n", VER_LEGALCOPYRIGHT_LOGO_STR_L);
+        printf("\n%s\n\n", VER_LEGALCOPYRIGHT_LOGO_STR);
         goto PrintUsageAndExit;
 
     ErrorExit:
@@ -391,7 +391,7 @@ extern "C" int _cdecl wmain(int argc, _In_ WCHAR **argv)
                             pAsm->m_wzResourceFile = pStr;
                         }
                         else
-                            printf("Multiple resource files not allowed. Option %ls skipped\n",argv[i]);
+                            printf("Multiple resource files not allowed. Last RES option skipped\n");
                     }
                     else if (!_stricmp(szOpt, "KEY"))
                     {
@@ -665,7 +665,7 @@ extern "C" int _cdecl wmain(int argc, _In_ WCHAR **argv)
                 if(bLogo)
                 {
                     printf("\n.NET IL Assembler.  Version " CLR_PRODUCT_VERSION);
-                    printf("\n%S", VER_LEGALCOPYRIGHT_LOGO_STR_L);
+                    printf("\n%s", VER_LEGALCOPYRIGHT_LOGO_STR);
                 }
 
                 pAsm->SetDLL(IsDLL);
@@ -848,14 +848,14 @@ extern "C" int _cdecl wmain(int argc, _In_ WCHAR **argv)
         wcscpy_s(pc+1,4,W("PDB"));
 
 #ifdef TARGET_WINDOWS
-        _wremove(wzOutputFilename);        
+        _wremove(wzOutputFilename);
 #else
         MAKE_UTF8PTR_FROMWIDE_NOTHROW(szOutputFilename, wzOutputFilename);
         if (szOutputFilename != NULL)
         {
             remove(szOutputFilename);
         }
-#endif        
+#endif
     }
     if (exitval == 0)
     {
diff --git a/src/coreclr/ildasm/dasm.cpp b/src/coreclr/ildasm/dasm.cpp
index 425f29e9222ab8..9f6c006015e544 100644
--- a/src/coreclr/ildasm/dasm.cpp
+++ b/src/coreclr/ildasm/dasm.cpp
@@ -1890,7 +1890,7 @@ BYTE* PrettyPrintCABlobValue(PCCOR_SIGNATURE &typePtr,
                 for(n=0; n < numElements; n++)
                 {
                     if(n) appendStr(out," ");
-                    sprintf_s(str,64,"%I64d",GET_UNALIGNED_VAL64(dataPtr));
+                    sprintf_s(str,64,"%lld",GET_UNALIGNED_VAL64(dataPtr));
                     appendStr(out,str);
                     dataPtr +=8;
                 }
@@ -1902,7 +1902,7 @@ BYTE* PrettyPrintCABlobValue(PCCOR_SIGNATURE &typePtr,
                 for(n=0; n < numElements; n++)
                 {
                     if(n) appendStr(out," ");
-                    sprintf_s(str,64,"%I64d",(ULONGLONG)GET_UNALIGNED_VAL64(dataPtr));
+                    sprintf_s(str,64,"%lld",(ULONGLONG)GET_UNALIGNED_VAL64(dataPtr));
                     appendStr(out,str);
                     dataPtr +=8;
                 }
@@ -1938,7 +1938,7 @@ BYTE* PrettyPrintCABlobValue(PCCOR_SIGNATURE &typePtr,
                     // Must compare as underlying bytes, not floating point otherwise optimizer will
                     // try to enregister and compare 80-bit precision number with 64-bit precision number!!!!
                     if((*(ULONGLONG*)&df != (ULONGLONG)GET_UNALIGNED_VAL64(dataPtr))||IsSpecialNumber(str))
-                        sprintf_s(str, 64, "0x%I64X",(ULONGLONG)GET_UNALIGNED_VAL64(dataPtr));
+                        sprintf_s(str, 64, "0x%llX",(ULONGLONG)GET_UNALIGNED_VAL64(dataPtr));
                     appendStr(out,str);
                     dataPtr +=8;
                 }
@@ -2597,10 +2597,10 @@ void DumpDefaultValue(mdToken tok, __inout __nullterminated char* szString, void
             szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr),"(%s)", KEYWORD((char *)(MDDV.m_byteValue ? "true" : "false")));
             break;
         case ELEMENT_TYPE_I8:
-            szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr)," = %s(0x%I64X)",KEYWORD("int64"),MDDV.m_ullValue);
+            szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr)," = %s(0x%llX)",KEYWORD("int64"),MDDV.m_ullValue);
             break;
         case ELEMENT_TYPE_U8:
-            szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr)," = %s(0x%I64X)",KEYWORD("uint64"),MDDV.m_ullValue);
+            szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr)," = %s(0x%llX)",KEYWORD("uint64"),MDDV.m_ullValue);
             break;
         case ELEMENT_TYPE_R4:
             {
@@ -2627,7 +2627,7 @@ void DumpDefaultValue(mdToken tok, __inout __nullterminated char* szString, void
                 if((*(ULONGLONG*)&df == MDDV.m_ullValue)&&!IsSpecialNumber(szf))
                     szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr)," = %s(%s)",KEYWORD("float64"),szf);
                 else
-                    szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr), " = %s(0x%I64X) // %s",KEYWORD("float64"),MDDV.m_ullValue,szf);
+                    szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr), " = %s(0x%llX) // %s",KEYWORD("float64"),MDDV.m_ullValue,szf);
             }
             break;
 
@@ -3743,7 +3743,7 @@ BOOL DumpMethod(mdToken FuncToken, const char *pszClassName, DWORD dwEntryPointT
                     sprintf_s(pszArgname[j].name,16,"A_%d",g_fThisIsInstanceMethod ? j+1 : j);
                 }
             }// end for( along the argnames)
-            sprintf_s(szArgPrefix,MAX_PREFIX_SIZE,"@%Id0",(size_t)pszArgname);
+            sprintf_s(szArgPrefix,MAX_PREFIX_SIZE,"@%zd0",(size_t)pszArgname);
         } //end if (ulArgs)
         g_pImport->EnumClose(&hArgEnum);
     }
diff --git a/src/coreclr/ildasm/dasm.rc b/src/coreclr/ildasm/dasm.rc
index 057398fe5253be..46c62cebd80be5 100644
--- a/src/coreclr/ildasm/dasm.rc
+++ b/src/coreclr/ildasm/dasm.rc
@@ -127,7 +127,6 @@ END
 
 STRINGTABLE DISCARDABLE
 BEGIN
-    IDS_USAGE_40            L"  /ALL        Combination of /HEADER, /BYTES, /TOKENS\n\n"
     IDS_USAGE_41            L"\nOption key is '-' or '/', options are recognized by first 3 characters\n\n"
     IDS_USAGE_42            L"Example:  ildasm /tok /byt myfile.exe /out=myfile.il\n\n"
     IDS_USAGE_43            L"\n\nPress any key to close the console window..."
@@ -203,8 +202,6 @@ END
 
 STRINGTABLE DISCARDABLE
 BEGIN
-    IDS_E_MULTIPLEINPUT     L"MULTIPLE INPUT FILES SPECIFIED\n\n"
-    IDS_E_INVALIDOPTION     L"INVALID COMMAND LINE OPTION: %s\n\n"
     IDS_W_CREATEDW32RES     L"WARNING: Created Win32 resource file %s"
     IDS_E_CORRUPTW32RES     L"ERROR: Corrupt Win32 resources"
     IDS_E_CANTOPENW32RES    L"ERROR: Unable to open file %s"
diff --git a/src/coreclr/ildasm/dis.cpp b/src/coreclr/ildasm/dis.cpp
index bc6a40e6d3cd8c..81ccc1928b8ff3 100644
--- a/src/coreclr/ildasm/dis.cpp
+++ b/src/coreclr/ildasm/dis.cpp
@@ -1029,7 +1029,7 @@ BOOL Disassemble(IMDInternalImport *pImport, BYTE *ILHeader, void *GUICookie, md
                 LoadScope(pRootScope,&daScope,&ulScopes);
                 qsort(&daScope[0],ulScopes,sizeof(LexScope),cmpLexScope);
                 OpenScope(pRootScope,pszLVname,ulVars);
-                sprintf_s(szVarPrefix,MAX_PREFIX_SIZE,"@%Id0",(size_t)pszLVname);
+                sprintf_s(szVarPrefix,MAX_PREFIX_SIZE,"@%zd0",(size_t)pszLVname);
 
 #ifndef SHOW_LEXICAL_SCOPES
                 for(unsigned jjj = 0; jjj < ulScopes; jjj++)
@@ -1540,7 +1540,7 @@ BOOL Disassemble(IMDInternalImport *pImport, BYTE *ILHeader, void *GUICookie, md
                     PadTheString;
                 }
 
-                szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr), "%-10s 0x%I64x", pszInstrName, v);
+                szptr+=sprintf_s(szptr,SZSTRING_REMAINING_SIZE(szptr), "%-10s 0x%llx", pszInstrName, v);
                 PC += 8;
                 break;
             }
diff --git a/src/coreclr/ildasm/resource.h b/src/coreclr/ildasm/resource.h
index 4995b4d28b85d9..64c246d2ca8a29 100644
--- a/src/coreclr/ildasm/resource.h
+++ b/src/coreclr/ildasm/resource.h
@@ -136,8 +136,6 @@
 #define IDS_E_MDIIMPORT                 456
 #define IDS_E_NOMANIFEST                457
 
-#define IDS_E_MULTIPLEINPUT             458
-#define IDS_E_INVALIDOPTION             459
 #define IDS_W_CREATEDW32RES             470
 #define IDS_E_CORRUPTW32RES             471
 #define IDS_E_CANTOPENW32RES            472
diff --git a/src/coreclr/ildasm/windasm.cpp b/src/coreclr/ildasm/windasm.cpp
index 490abb53775c89..d85e5277e45171 100644
--- a/src/coreclr/ildasm/windasm.cpp
+++ b/src/coreclr/ildasm/windasm.cpp
@@ -94,22 +94,22 @@ FILE* OpenOutput(_In_ __nullterminated const char* szFileName);
 void PrintLogo()
 {
     printf(".NET IL Disassembler.  Version " CLR_PRODUCT_VERSION);
-    printf("\n%S\n\n", VER_LEGALCOPYRIGHT_LOGO_STR_L);
+    printf("\n%s\n\n", VER_LEGALCOPYRIGHT_LOGO_STR);
 }
 
 void SyntaxCon()
 {
     DWORD l;
 
-    for(l=IDS_USAGE_01; l<= IDS_USAGE_23; l++) printf(RstrANSI(l));
+    for(l=IDS_USAGE_01; l<= IDS_USAGE_23; l++) printf("%s", RstrANSI(l));
     if(g_fTDC)
     {
-        for(l=IDS_USAGE_24; l<= IDS_USAGE_32; l++) printf(RstrANSI(l));
-        for(l=IDS_USAGE_34; l<= IDS_USAGE_36; l++) printf(RstrANSI(l));
-        for(l=IDS_USAGE_37; l<= IDS_USAGE_39; l++) printf(RstrANSI(l));
+        for(l=IDS_USAGE_24; l<= IDS_USAGE_32; l++) printf("%s", RstrANSI(l));
+        for(l=IDS_USAGE_34; l<= IDS_USAGE_36; l++) printf("%s", RstrANSI(l));
+        for(l=IDS_USAGE_37; l<= IDS_USAGE_39; l++) printf("%s", RstrANSI(l));
     }
-    else printf(RstrANSI(IDS_USAGE_40));
-    for(l=IDS_USAGE_41; l<= IDS_USAGE_42; l++) printf(RstrANSI(l));
+    else printf("  /ALL        Combination of /HEADER, /BYTES, /TOKENS\n\n");
+    for(l=IDS_USAGE_41; l<= IDS_USAGE_42; l++) printf("%s", RstrANSI(l));
 
 }
 
@@ -403,7 +403,7 @@ int ProcessOneArg(_In_ __nullterminated char* szArg, _Out_ char** ppszObjFileNam
         else
         {
             PrintLogo();
-            printf(RstrANSI(IDS_E_INVALIDOPTION),szArg); //"INVALID COMMAND LINE OPTION: %s\n\n",szArg);
+            printf("INVALID COMMAND LINE OPTION: %s\n\n",szArg);
             return -1;
         }
     }
@@ -412,7 +412,7 @@ int ProcessOneArg(_In_ __nullterminated char* szArg, _Out_ char** ppszObjFileNam
         if(g_szInputFile[0])
         {
             PrintLogo();
-            printf(RstrANSI(IDS_E_MULTIPLEINPUT)); //"MULTIPLE INPUT FILES SPECIFIED\n\n");
+            printf("MULTIPLE INPUT FILES SPECIFIED\n\n");
             return -1; // check if it was already specified
         }
         szArg = CheckForDQuotes(szArg);
diff --git a/src/coreclr/inc/clrversion.h b/src/coreclr/inc/clrversion.h
index 5058a47d6d3878..841fb24f126009 100644
--- a/src/coreclr/inc/clrversion.h
+++ b/src/coreclr/inc/clrversion.h
@@ -26,4 +26,3 @@
 #define VER_FILEVERSION_STR_L       QUOTE_MACRO_L(RuntimeFileMajorVersion.RuntimeFileMinorVersion.RuntimeFileBuildVersion.RuntimeFileRevisionVersion)
 
 #define VER_LEGALCOPYRIGHT_LOGO_STR    "Copyright (c) Microsoft Corporation.  All rights reserved."
-#define VER_LEGALCOPYRIGHT_LOGO_STR_L L"Copyright (c) Microsoft Corporation.  All rights reserved."
diff --git a/src/coreclr/inc/formattype.cpp b/src/coreclr/inc/formattype.cpp
index a1b2e043ee3c69..6a79d4b6e5f354 100644
--- a/src/coreclr/inc/formattype.cpp
+++ b/src/coreclr/inc/formattype.cpp
@@ -1507,7 +1507,7 @@ char* DumpMarshaling(IMDInternalImport* pImport,
         buf.AppendASCII(" }) ");
 
         char * tgt = szString + strlen(szString);
-        int sprintf_ret = sprintf_s(tgt, cchszString - (tgt - szString), "%S", buf.GetUnicode());
+        int sprintf_ret = sprintf_s(tgt, cchszString - (tgt - szString), "%s", buf.GetUTF8());
         if (sprintf_ret == -1)
         {
             // Hit an error. Oh well, nothing to do...
@@ -1521,7 +1521,7 @@ char* DumpMarshaling(IMDInternalImport* pImport,
     else
     {
         char * tgt = szString + strlen(szString);
-        int sprintf_ret = sprintf_s(tgt, cchszString - (tgt - szString), "%S", buf.GetUnicode());
+        int sprintf_ret = sprintf_s(tgt, cchszString - (tgt - szString), "%s", buf.GetUTF8());
         if (sprintf_ret == -1)
         {
             // There was an error, possibly with converting the Unicode characters.
diff --git a/src/coreclr/inc/gcmsg.inl b/src/coreclr/inc/gcmsg.inl
index f6e1f7227a1c45..bb95800a015f48 100644
--- a/src/coreclr/inc/gcmsg.inl
+++ b/src/coreclr/inc/gcmsg.inl
@@ -44,13 +44,13 @@
     static const char* gcDetailedStartMsg()
     {
         STATIC_CONTRACT_LEAF;
-        return "*GC* %d(gen0:%d)(%d)(alloc: %Id)(%s)(%d)";
+        return "*GC* %d(gen0:%d)(%d)(alloc: %zd)(%s)(%d)";
     }
 
     static const char* gcDetailedEndMsg()
     {
         STATIC_CONTRACT_LEAF;
-        return "*EGC* %Id(gen0:%Id)(%Id)(%d)(%s)(%s)(%s)(ml: %d->%d)";
+        return "*EGC* %zd(gen0:%zd)(%zd)(%d)(%s)(%s)(%s)(ml: %d->%d)";
     }
 
     static const char* gcStartMarkMsg()
@@ -80,7 +80,7 @@
     static const char* gcStartCompactMsg()
     {
         STATIC_CONTRACT_LEAF;
-        return "---- Compact Phase on heap %d: %Ix(%Ix)----";
+        return "---- Compact Phase on heap %d: %zx(%zx)----";
     }
 
     static const char* gcEndCompactMsg()
@@ -92,31 +92,31 @@
     static const char* gcMemCopyMsg()
     {
         STATIC_CONTRACT_LEAF;
-        return " mc: [%Ix->%Ix, %Ix->%Ix[";
+        return " mc: [%zx->%zx, %zx->%zx[";
     }
 
     static const char* gcPlanPlugMsg()
     {
         STATIC_CONTRACT_LEAF;
-        return "(%Ix)[%Ix->%Ix, NA: [%Ix(%Id), %Ix[: %Ix(%d), x: %Ix (%s)";
+        return "(%zx)[%zx->%zx, NA: [%zx(%zd), %zx[: %zx(%d), x: %zx (%s)";
     }
 
     static const char* gcPlanPinnedPlugMsg()
     {
         STATIC_CONTRACT_LEAF;
-        return "(%Ix)PP: [%Ix, %Ix[%Ix](m:%d)";
+        return "(%zx)PP: [%zx, %zx[%zx](m:%d)";
     }
 
     static const char* gcDesiredNewAllocationMsg()
     {
         STATIC_CONTRACT_LEAF;
-        return "h%d g%d surv: %Id current: %Id alloc: %Id (%d%%) f: %d%% new-size: %Id new-alloc: %Id";
+        return "h%d g%d surv: %zd current: %zd alloc: %zd (%d%%) f: %d%% new-size: %zd new-alloc: %zd";
     }
 
     static const char* gcMakeUnusedArrayMsg()
     {
         STATIC_CONTRACT_LEAF;
-        return "Making unused array [%Ix, %Ix[";
+        return "Making unused array [%zx, %zx[";
     }
 
     static const char* gcStartBgcThread()
diff --git a/src/coreclr/jit/assertionprop.cpp b/src/coreclr/jit/assertionprop.cpp
index 980bfcfb5dd97a..2c3fca0a28b233 100644
--- a/src/coreclr/jit/assertionprop.cpp
+++ b/src/coreclr/jit/assertionprop.cpp
@@ -4235,7 +4235,7 @@ GenTree* Compiler::optAssertionPropGlobal_RelOp(ASSERT_VALARG_TP assertions, Gen
             }
             else if (op1->TypeGet() == TYP_LONG)
             {
-                printf("%I64d\n", vnStore->ConstantValue<INT64>(vnCns));
+                printf("%lld\n", vnStore->ConstantValue<INT64>(vnCns));
             }
             else if (op1->TypeGet() == TYP_DOUBLE)
             {
diff --git a/src/coreclr/jit/compiler.cpp b/src/coreclr/jit/compiler.cpp
index 41235431b38f62..78fff4c4321747 100644
--- a/src/coreclr/jit/compiler.cpp
+++ b/src/coreclr/jit/compiler.cpp
@@ -8607,7 +8607,7 @@ void JitTimer::PrintCsvMethodStats(Compiler* comp)
         {
             totCycles += m_info.m_cyclesByPhase[i];
         }
-        fprintf(s_csvFile, "%I64u,", m_info.m_cyclesByPhase[i]);
+        fprintf(s_csvFile, "%llu,", m_info.m_cyclesByPhase[i]);
 
         if ((JitConfig.JitMeasureIR() != 0) && PhaseReportsIRSize[i])
         {
@@ -8618,9 +8618,9 @@ void JitTimer::PrintCsvMethodStats(Compiler* comp)
     comp->m_inlineStrategy->DumpCsvData(s_csvFile);
 
     fprintf(s_csvFile, "%u,", comp->info.compNativeCodeSize);
-    fprintf(s_csvFile, "%Iu,", comp->compInfoBlkSize);
-    fprintf(s_csvFile, "%Iu,", comp->compGetArenaAllocator()->getTotalBytesAllocated());
-    fprintf(s_csvFile, "%I64u,", m_info.m_totalCycles);
+    fprintf(s_csvFile, "%zu,", comp->compInfoBlkSize);
+    fprintf(s_csvFile, "%zu,", comp->compGetArenaAllocator()->getTotalBytesAllocated());
+    fprintf(s_csvFile, "%llu,", m_info.m_totalCycles);
     fprintf(s_csvFile, "%f\n", CachedCyclesPerSecond());
 
     fflush(s_csvFile);
diff --git a/src/coreclr/jit/disasm.cpp b/src/coreclr/jit/disasm.cpp
index 10fb136eb2b364..5f01c4eea6d72c 100644
--- a/src/coreclr/jit/disasm.cpp
+++ b/src/coreclr/jit/disasm.cpp
@@ -389,7 +389,7 @@ size_t DisAssembler::disCchFixupMember(
             if (anyReloc)
             {
                 // Make instructions like "mov rcx, 7FE8247A638h" diffable.
-                swprintf_s(wz, cchMax, W("%IXh"), dspAddr(targetAddr));
+                swprintf_s(wz, cchMax, W("%zXh"), dspAddr(targetAddr));
                 break;
             }
 
@@ -494,7 +494,7 @@ size_t DisAssembler::disCchFixupMember(
                  * "addr" is the address of the immediate */
 
                 // Make instructions like "mov rcx, 7FE8247A638h" diffable.
-                swprintf_s(wz, cchMax, W("%IXh"), dspAddr(targetAddr));
+                swprintf_s(wz, cchMax, W("%zXh"), dspAddr(targetAddr));
                 break;
             }
 
@@ -913,9 +913,9 @@ size_t DisAssembler::CbDisassemble(DIS*        pdis,
 
     if (cb == 0)
     {
-        DISASM_DUMP("CbDisassemble offs %Iu addr %I64u\n", offs, addr);
+        DISASM_DUMP("CbDisassemble offs %zu addr %llu\n", offs, addr);
         // assert(!"can't disassemble instruction!!!");
-        fprintf(pfile, "MSVCDIS can't disassemble instruction @ offset %Iu (0x%02x)!!!\n", offs, offs);
+        fprintf(pfile, "MSVCDIS can't disassemble instruction @ offset %zu (0x%02zx)!!!\n", offs, offs);
 #if defined(TARGET_ARM64)
         fprintf(pfile, "%08Xh\n", *(unsigned int*)pb);
         return 4;
diff --git a/src/coreclr/jit/emitxarch.cpp b/src/coreclr/jit/emitxarch.cpp
index 6530f535d71106..3ff690302d9a9f 100644
--- a/src/coreclr/jit/emitxarch.cpp
+++ b/src/coreclr/jit/emitxarch.cpp
@@ -9626,7 +9626,7 @@ void emitter::emitDispReloc(ssize_t value)
     }
     else
     {
-        printf("(reloc 0x%Ix)", emitComp->dspPtr(value));
+        printf("(reloc 0x%zx)", emitComp->dspPtr(value));
     }
 }
 
@@ -10163,11 +10163,11 @@ void emitter::emitDispIns(
                 }
                 else if ((val > 0) || (val < -0xFFFFFF))
                 {
-                    printf("0x%IX", (ssize_t)val);
+                    printf("0x%zX", (ssize_t)val);
                 }
                 else
                 { // (val < 0)
-                    printf("-0x%IX", (ssize_t)-val);
+                    printf("-0x%zX", (ssize_t)-val);
                 }
                 emitDispCommentForHandle(srcVal, id->idDebugOnlyInfo()->idMemCookie, id->idDebugOnlyInfo()->idFlags);
             }
diff --git a/src/coreclr/jit/unwind.cpp b/src/coreclr/jit/unwind.cpp
index ea9ee5787aaa79..12114916f5362c 100644
--- a/src/coreclr/jit/unwind.cpp
+++ b/src/coreclr/jit/unwind.cpp
@@ -400,7 +400,7 @@ void Compiler::DumpCfiInfo(bool                  isHotCode,
                 printf("    CodeOffset: 0x%02X Op: AdjustCfaOffset Offset:0x%X\n", codeOffset, offset);
                 break;
             default:
-                printf("    Unrecognized CFI_CODE: 0x%IX\n", *(UINT64*)pCode);
+                printf("    Unrecognized CFI_CODE: 0x%llX\n", *(UINT64*)pCode);
                 break;
         }
     }
diff --git a/src/coreclr/md/enc/stgtiggerstorage.cpp b/src/coreclr/md/enc/stgtiggerstorage.cpp
index a216961ffe6e4a..4c9869eb8caa23 100644
--- a/src/coreclr/md/enc/stgtiggerstorage.cpp
+++ b/src/coreclr/md/enc/stgtiggerstorage.cpp
@@ -967,7 +967,7 @@ ULONG TiggerStorage::PrintSizeInfo(bool verbose)
         for (int i = 0; i < m_StgHdr.GetiStreams(); i++)
         {
             pNext = storStream->NextStream();
-            printf("Stream #%d (%s) Header: %zd, Data: %lu\n",i,storStream->GetName(), (size_t)((BYTE*)pNext - (BYTE*)storStream), storStream->GetSize());
+            printf("Stream #%d (%s) Header: %zd, Data: %u\n",i,storStream->GetName(), (size_t)((BYTE*)pNext - (BYTE*)storStream), storStream->GetSize());
             total += storStream->GetSize();
             storStream = pNext;
         }
diff --git a/src/coreclr/pal/src/cruntime/printfcpp.cpp b/src/coreclr/pal/src/cruntime/printfcpp.cpp
index a2b9c8f004dee7..198d26ed740e96 100644
--- a/src/coreclr/pal/src/cruntime/printfcpp.cpp
+++ b/src/coreclr/pal/src/cruntime/printfcpp.cpp
@@ -359,8 +359,6 @@ BOOL Internal_ExtractFormatA(CPalThread *pthrCurrent, LPCSTR *Fmt, LPSTR Out, LP
                 *Out++ = '1';
                 *Out++ = '6';
             }
-            /* native *printf does not support %I64p
-               (actually %llp), so we need to cheat a little bit */
             *Out++ = 'l';
             *Out++ = 'l';
         }
diff --git a/src/coreclr/pal/src/map/virtual.cpp b/src/coreclr/pal/src/map/virtual.cpp
index e11f39cd4be16f..ad5fc4ce9aaa6e 100644
--- a/src/coreclr/pal/src/map/virtual.cpp
+++ b/src/coreclr/pal/src/map/virtual.cpp
@@ -1276,7 +1276,7 @@ PAL_VirtualReserveFromExecutableMemoryAllocatorWithinRange(
 #ifdef HOST_64BIT
     PERF_ENTRY(PAL_VirtualReserveFromExecutableMemoryAllocatorWithinRange);
     ENTRY(
-        "PAL_VirtualReserveFromExecutableMemoryAllocatorWithinRange(lpBeginAddress = %p, lpEndAddress = %p, dwSize = %Iu, fStoreAllocationInfo = %d)\n",
+        "PAL_VirtualReserveFromExecutableMemoryAllocatorWithinRange(lpBeginAddress = %p, lpEndAddress = %p, dwSize = %zu, fStoreAllocationInfo = %d)\n",
         lpBeginAddress,
         lpEndAddress,
         dwSize,
diff --git a/src/coreclr/pal/src/thread/thread.cpp b/src/coreclr/pal/src/thread/thread.cpp
index 6d614b7e37ed56..0daa011e6fc636 100644
--- a/src/coreclr/pal/src/thread/thread.cpp
+++ b/src/coreclr/pal/src/thread/thread.cpp
@@ -572,7 +572,7 @@ CorUnix::InternalCreateThread(
             // When coming here from the public API surface, the incoming value is originally a nonnegative signed int32, so
             // this shouldn't happen
             ASSERT(
-                "Couldn't align the requested stack size (%Iu) to the page size because the stack size was too large\n",
+                "Couldn't align the requested stack size (%zu) to the page size because the stack size was too large\n",
                 alignedStackSize);
             palError = ERROR_INVALID_PARAMETER;
             goto EXIT;
@@ -645,10 +645,10 @@ CorUnix::InternalCreateThread(
             alignedStackSize = MinStackSize;
         }
 
-        TRACE("setting thread stack size to %Iu\n", alignedStackSize);
+        TRACE("setting thread stack size to %zu\n", alignedStackSize);
         if (0 != pthread_attr_setstacksize(&pthreadAttr, alignedStackSize))
         {
-            ERROR("couldn't set pthread stack size to %Iu\n", alignedStackSize);
+            ERROR("couldn't set pthread stack size to %zu\n", alignedStackSize);
             palError = ERROR_INTERNAL_ERROR;
             goto EXIT;
         }
diff --git a/src/coreclr/tools/StressLogAnalyzer/StressLogPlugin.cpp b/src/coreclr/tools/StressLogAnalyzer/StressLogPlugin.cpp
index 4a4141490e6be9..eb276755d21884 100644
--- a/src/coreclr/tools/StressLogAnalyzer/StressLogPlugin.cpp
+++ b/src/coreclr/tools/StressLogAnalyzer/StressLogPlugin.cpp
@@ -562,7 +562,7 @@ static volatile LONG64 s_msgCount = 0;
 static volatile LONG64 s_totalMsgCount = 0;
 static double s_timeFilterStart = 0;
 static double s_timeFilterEnd = 0;
-static WCHAR* s_outputFileName = nullptr;
+static const char* s_outputFileName = nullptr;
 
 static StressLog::StressLogHeader* s_hdr;
 
@@ -591,7 +591,7 @@ void Usage()
     printf(" -f: print the raw format strings along with the message\n");
     printf("     (useful to search for the format string in the source code)\n");
     printf(" -f:<format string>: search for a specific format string\n");
-    printf("    e.g. '-f:\"<%%Ix>:%%Ix\"'\n");
+    printf("    e.g. '-f:\"<%%zx>:%%zx\"'\n");
     printf("\n");
     printf(" -i:<hex facility code>: ignore messages from log facilities\n");
     printf("   e.g. '-i:7ffe' means ignore messages from anything but LF_GC\n");
@@ -779,10 +779,7 @@ bool ParseOptions(int argc, char* argv[])
             case 'O':
                 if (arg[2] == ':')
                 {
-                    WCHAR* buffer = new WCHAR[1000];
-                    if (MultiByteToWideChar(CP_ACP, 0, &arg[3], -1, buffer, 1000) == 0)
-                        return false;
-                    s_outputFileName = buffer;
+                    s_outputFileName = &arg[3];
                 }
                 else
                 {
@@ -1036,14 +1033,14 @@ DWORD WINAPI ProcessStresslogWorker(LPVOID)
         {
             wrappedWriteThreadCount++;
         }
-        // printf("thread: %Ix\n", tsl->threadId);
+        // printf("thread: %zx\n", tsl->threadId);
         StressMsg* msg = StressLog::TranslateMemoryMappedPointer(tsl->curPtr);
         StressLogChunk* slc = StressLog::TranslateMemoryMappedPointer(tsl->curWriteChunk);
         int chunkCount = 0;
         StressMsg* prevMsg = nullptr;
         while (true)
         {
-            // printf("stress log chunk %Ix\n", (size_t)slc);
+            // printf("stress log chunk %zx\n", (size_t)slc);
             if (!slc->IsValid())
             {
                 printf("oops, invalid stress log chunk\n");
@@ -1399,9 +1396,9 @@ int ProcessStressLog(void* baseAddress, int argc, char* argv[])
     FILE* outputFile = stdout;
     if (s_outputFileName != nullptr)
     {
-        if (_wfopen_s(&outputFile, s_outputFileName, W("w")) != 0)
+        if (fopen_s(&outputFile, s_outputFileName, "w") != 0)
         {
-            printf("could not create output file %S\n", s_outputFileName);
+            printf("could not create output file %s\n", s_outputFileName);
             outputFile = stdout;
         }
     }
@@ -1485,7 +1482,7 @@ int ProcessStressLog(void* baseAddress, int argc, char* argv[])
         (double)usedSize / (1024 * 1024 * 1024), (double)availSize/ (1024 * 1024 * 1024),
         s_threadStressLogCount, (int)s_wrappedWriteThreadCount);
     if (hdr->threadsWithNoLog != 0)
-        printf("%Id threads did not get a log!\n", hdr->threadsWithNoLog);
+        printf("%lld threads did not get a log!\n", hdr->threadsWithNoLog);
     printf("Number of messages examined: "); PrintFriendlyNumber(s_totalMsgCount); printf(", printed: "); PrintFriendlyNumber(s_msgCount); printf("\n");
 
     delete[] s_threadMsgBuf;
diff --git a/src/coreclr/tools/metainfo/mdinfo.cpp b/src/coreclr/tools/metainfo/mdinfo.cpp
index 6d35f03e8d9faa..9f3e16f5d70d5f 100644
--- a/src/coreclr/tools/metainfo/mdinfo.cpp
+++ b/src/coreclr/tools/metainfo/mdinfo.cpp
@@ -360,7 +360,7 @@ void MDInfo::DisplayMD()
         // WriteLine("Unresolved MemberRefs");
         // DisplayMemberRefs(0x00000001, "\t");
 
-        VWrite("\n\nCoff symbol name overhead:  %Iu\n", g_cbCoffNames);
+        VWrite("\n\nCoff symbol name overhead:  %zu\n", g_cbCoffNames);
     }
     WriteLine("===========================================================");
     if (m_DumpFilter & dumpUnsat)
@@ -2196,7 +2196,7 @@ LPCWSTR MDInfo::VariantAsString(VARIANT *pVariant)
         // Set variant type to bstr.
         V_VT(pVariant) = VT_BSTR;
         // Create the ansi string.
-        sprintf_s(szStr, 32, "%I64d", V_CY(pVariant).int64);
+        sprintf_s(szStr, 32, "%lld", V_CY(pVariant).int64);
         // Convert to unicode.
         WszMultiByteToWideChar(CP_ACP, 0, szStr, -1, wszStr, 32);
         // convert to bstr and set variant value.
diff --git a/src/coreclr/tools/superpmi/mcs/verbildump.cpp b/src/coreclr/tools/superpmi/mcs/verbildump.cpp
index 506d14e587f992..e29b92ac277025 100644
--- a/src/coreclr/tools/superpmi/mcs/verbildump.cpp
+++ b/src/coreclr/tools/superpmi/mcs/verbildump.cpp
@@ -909,8 +909,7 @@ char* DumpAttributeToConsoleBare(DWORD attribute)
 #define ifPrint(s, t)                                                                                                  \
     else if ((s & attribute) == s)                                                                                     \
     {                                                                                                                  \
-        printf(t);                                                                                                     \
-        printf(" ");                                                                                                   \
+        printf("%s ", t);                                                                                              \
     }
 
     if (0)
diff --git a/src/coreclr/tools/superpmi/superpmi-shared/lightweightmap.h b/src/coreclr/tools/superpmi/superpmi-shared/lightweightmap.h
index e696f469d17dfa..28b61e6eb8eb4e 100644
--- a/src/coreclr/tools/superpmi/superpmi-shared/lightweightmap.h
+++ b/src/coreclr/tools/superpmi/superpmi-shared/lightweightmap.h
@@ -265,7 +265,7 @@ class LightWeightMap : public LightWeightMapBuffer
 
         // If we have RTTI, we can make this assert report the correct type. No RTTI, though, when
         // built with .NET Core, especially when built against the PAL.
-        AssertCodeMsg((unsigned int)(ptr - rawData) == size, EXCEPTIONCODE_LWM, "%s - Ended with unexpected sizes %Ix != %x",
+        AssertCodeMsg((unsigned int)(ptr - rawData) == size, EXCEPTIONCODE_LWM, "%s - Ended with unexpected sizes %zx != %x",
                       "Unknown type" /*typeid(_Item).name()*/, ptr - rawData, size);
     }
 
@@ -549,7 +549,7 @@ class DenseLightWeightMap : public LightWeightMapBuffer
             ptr += bufferLength * sizeof(unsigned char);
         }
 
-        AssertCodeMsg((unsigned int)(ptr - rawData) == size, EXCEPTIONCODE_LWM, "Ended with unexpected sizes %Ix != %x",
+        AssertCodeMsg((unsigned int)(ptr - rawData) == size, EXCEPTIONCODE_LWM, "Ended with unexpected sizes %zx != %x",
                       ptr - rawData, size);
     }
 
@@ -609,7 +609,7 @@ class DenseLightWeightMap : public LightWeightMapBuffer
             delete[] tItems;
         }
 
-        AssertCodeMsg((unsigned int)(ptr - rawData) == size, EXCEPTIONCODE_LWM, "Ended with unexpected sizes %Ix != %x",
+        AssertCodeMsg((unsigned int)(ptr - rawData) == size, EXCEPTIONCODE_LWM, "Ended with unexpected sizes %zx != %x",
                       ptr - rawData, size);
     }
 
@@ -656,7 +656,7 @@ class DenseLightWeightMap : public LightWeightMapBuffer
             ptr += bufferLength * sizeof(unsigned char);
         }
 
-        AssertCodeMsg(ptr == (bytes + size), EXCEPTIONCODE_LWM, "Ended with unexpected sizes %Ix != %x", ptr - bytes,
+        AssertCodeMsg(ptr == (bytes + size), EXCEPTIONCODE_LWM, "Ended with unexpected sizes %zx != %x", ptr - bytes,
                       size);
         return size;
     }
diff --git a/src/coreclr/unwinder/amd64/dbs_stack_x64.cpp b/src/coreclr/unwinder/amd64/dbs_stack_x64.cpp
index c76956e663e630..e60e7c33fa1048 100644
--- a/src/coreclr/unwinder/amd64/dbs_stack_x64.cpp
+++ b/src/coreclr/unwinder/amd64/dbs_stack_x64.cpp
@@ -127,10 +127,10 @@ Routine Description:
     MachineFrame = FALSE;
     PrologOffset = (ULONG)(ControlPc - (FunctionEntry->BeginAddress + ImageBase));
 
-    m_Services->Status(1, "Prol: RIP %I64X, 0x%X bytes in function at %I64X\n",
+    m_Services->Status(1, "Prol: RIP %llX, 0x%X bytes in function at %llX\n",
                        ControlPc, PrologOffset,
                        FunctionEntry->BeginAddress + ImageBase);
-    m_Services->Status(1, "Prol: Read unwind info at %I64X\n",
+    m_Services->Status(1, "Prol: Read unwind info at %llX\n",
                        FunctionEntry->UnwindInfoAddress + ImageBase);
 
     if ((Status =
@@ -147,7 +147,7 @@ Routine Description:
 
     while (Index < UnwindInfo->CountOfCodes) {
 
-        m_Services->Status(1, "  %02X: Code %X offs %03X, RSP %I64X\n",
+        m_Services->Status(1, "  %02X: Code %X offs %03X, RSP %llX\n",
              Index, UnwindInfo->UnwindCode[Index].UnwindOp,
              UnwindInfo->UnwindCode[Index].CodeOffset,
              ContextRecord->Rsp);
@@ -182,7 +182,7 @@ Routine Description:
                                    &IntegerRegister[OpInfo],
                                    sizeof(ULONG64))) != S_OK) {
                     m_Services->Status(1, "Prol: Op %X memory "
-                                       "read failed at %I64X\n",
+                                       "read failed at %llX\n",
                                        UnwindOp, IntegerAddress);
                     goto Fail;
                 }
@@ -249,7 +249,7 @@ Routine Description:
                                   &IntegerRegister[OpInfo],
                                   sizeof(ULONG64))) != S_OK) {
                     m_Services->Status(1, "Prol: Op %X memory read "
-                                       "failed at %I64X\n",
+                                       "failed at %llX\n",
                                        UnwindOp, IntegerAddress);
                     goto Fail;
                 }
@@ -272,7 +272,7 @@ Routine Description:
                                    &IntegerRegister[OpInfo],
                                    sizeof(ULONG64))) != S_OK) {
                     m_Services->Status(1, "Prol: Op %X memory read "
-                                       "failed at %I64X\n",
+                                       "failed at %llX\n",
                                        UnwindOp, IntegerAddress);
                     goto Fail;
                 }
@@ -295,7 +295,7 @@ Routine Description:
                                    &FloatingRegister[OpInfo].Low,
                                    sizeof(ULONG64))) != S_OK) {
                     m_Services->Status(1, "Prol: Op %X memory read "
-                                       "failed at %I64X\n",
+                                       "failed at %llX\n",
                                        UnwindOp, FloatingAddress);
                     goto Fail;
                 }
@@ -319,7 +319,7 @@ Routine Description:
                                    &FloatingRegister[OpInfo].Low,
                                    sizeof(ULONG64))) != S_OK) {
                     m_Services->Status(1, "Prol: Op %X memory read "
-                                       "failed at %I64X\n",
+                                       "failed at %llX\n",
                                        UnwindOp, FloatingAddress);
                     goto Fail;
                 }
@@ -341,7 +341,7 @@ Routine Description:
                                    &FloatingRegister[OpInfo],
                                    sizeof(AMD64_M128))) != S_OK) {
                     m_Services->Status(1, "Prol: Op %X memory read "
-                                       "failed at %I64X\n",
+                                       "failed at %llX\n",
                                        UnwindOp, FloatingAddress);
                     goto Fail;
                 }
@@ -364,7 +364,7 @@ Routine Description:
                                    &FloatingRegister[OpInfo],
                                    sizeof(AMD64_M128))) != S_OK) {
                     m_Services->Status(1, "Prol: Op %X memory read "
-                                       "failed at %I64X\n",
+                                       "failed at %llX\n",
                                        UnwindOp, FloatingAddress);
                     goto Fail;
                 }
@@ -395,7 +395,7 @@ Routine Description:
                                    &ContextRecord->Rip,
                                    sizeof(ULONG64))) != S_OK) {
                     m_Services->Status(1, "Prol: Op %X memory "
-                                       "read 1 failed at %I64X\n",
+                                       "read 1 failed at %llX\n",
                                        UnwindOp, ReturnAddress);
                     goto Fail;
                 }
@@ -404,7 +404,7 @@ Routine Description:
                                    &ContextRecord->Rsp,
                                    sizeof(ULONG64))) != S_OK) {
                     m_Services->Status(1, "Prol: Op %X memory "
-                                       "read 2 failed at %I64X\n",
+                                       "read 2 failed at %llX\n",
                                        UnwindOp, StackAddress);
                     goto Fail;
                 }
@@ -480,7 +480,7 @@ Routine Description:
         ChainEntry = (_PIMAGE_RUNTIME_FUNCTION_ENTRY)
             &UnwindInfo->UnwindCode[Index];
 
-        m_Services->Status(1, "  Chain with entry at %I64X\n",
+        m_Services->Status(1, "  Chain with entry at %llX\n",
              FunctionEntry->UnwindInfoAddress + ImageBase +
              (ULONG64)((PUCHAR)&UnwindInfo->UnwindCode[Index] -
                        (PUCHAR)UnwindInfo));
@@ -507,7 +507,7 @@ Routine Description:
             ContextRecord->Rsp += 8;
         }
 
-        m_Services->Status(1, "Prol: Returning with RIP %I64X, RSP %I64X\n",
+        m_Services->Status(1, "Prol: Returning with RIP %llX, RSP %llX\n",
                            ContextRecord->Rip, ContextRecord->Rsp);
         return S_OK;
     }
@@ -660,7 +660,7 @@ Routine Description:
     if ((Status = m_Services->
          ReadMemory(ControlPc, InstrBuffer, sizeof(InstrBuffer),
                     &InstrBytes)) != S_OK) {
-        m_Services->Status(1, "Unable to read instruction stream at %I64X\n",
+        m_Services->Status(1, "Unable to read instruction stream at %llX\n",
                            ControlPc);
 
         // We need the code to look for epilogue ops.
@@ -966,7 +966,7 @@ Routine Description:
                     ReadAllMemory(ContextRecord->Rsp,
                                   &IntegerRegister[RegisterNumber],
                                   sizeof(ULONG64))) != S_OK) {
-                    m_Services->Status(1, "Unable to read stack at %I64X\n",
+                    m_Services->Status(1, "Unable to read stack at %llX\n",
                          ContextRecord->Rsp);
                     return Status;
                 }
@@ -987,7 +987,7 @@ Routine Description:
                      ReadAllMemory(ContextRecord->Rsp,
                                    &IntegerRegister[RegisterNumber],
                                    sizeof(ULONG64))) != S_OK) {
-                    m_Services->Status(1, "Unable to read stack at %I64X\n",
+                    m_Services->Status(1, "Unable to read stack at %llX\n",
                          ContextRecord->Rsp);
                     return Status;
                 }
@@ -1011,7 +1011,7 @@ Routine Description:
             ReadAllMemory(ContextRecord->Rsp,
                           &ContextRecord->Rip,
                           sizeof(ULONG64))) != S_OK) {
-            m_Services->Status(1, "Unable to read stack at %I64X\n",
+            m_Services->Status(1, "Unable to read stack at %llX\n",
                  ContextRecord->Rsp);
             return Status;
         }
@@ -1467,7 +1467,7 @@ DbsX64StackUnwinder::BaseUnwind(void)
         // directly to the return address.
         //
 
-        m_Services->Status(1, "Leaf %I64X RSP %I64X\n",
+        m_Services->Status(1, "Leaf %llX RSP %llX\n",
                            m_Context.Rip, m_Context.Rsp);
 
         if ((Status = m_Services->
diff --git a/src/coreclr/utilcode/debug.cpp b/src/coreclr/utilcode/debug.cpp
index eadce8075bdaf4..dfc323744363c0 100644
--- a/src/coreclr/utilcode/debug.cpp
+++ b/src/coreclr/utilcode/debug.cpp
@@ -265,9 +265,9 @@ bool _DbgBreakCheck(
         OutputDebugStringUtf8("\n");
         OutputDebugStringUtf8(szExpr);
         OutputDebugStringUtf8("\n");
-        printf(szLowMemoryAssertMessage);
+        printf("%s", szLowMemoryAssertMessage);
         printf("\n");
-        printf(szFile);
+        printf("%s", szFile);
         printf("\n");
         printf("%s", szExpr);
         printf("\n");
@@ -524,7 +524,7 @@ void DECLSPEC_NORETURN __FreeBuildAssertFail(const char *szFile, int iLine, cons
     OutputDebugStringUtf8(buffer.GetUTF8());
 
     // Write out the error to the console
-    printf(buffer.GetUTF8());
+    printf("%s", buffer.GetUTF8());
 
     // Log to the stress log. Note that we can't include the szExpr b/c that
     // may not be a string literal (particularly for formatt-able asserts).
diff --git a/src/coreclr/utilcode/executableallocator.cpp b/src/coreclr/utilcode/executableallocator.cpp
index 078800995d1334..dbaf2f52ebac2f 100644
--- a/src/coreclr/utilcode/executableallocator.cpp
+++ b/src/coreclr/utilcode/executableallocator.cpp
@@ -81,15 +81,15 @@ void ExecutableAllocator::DumpHolderUsage()
     LARGE_INTEGER freq;
     QueryPerformanceFrequency(&freq);
 
-    fprintf(stderr, "Map time with lock sum: %I64dms\n", g_mapTimeWithLockSum / (freq.QuadPart / 1000));
-    fprintf(stderr, "Map time sum: %I64dms\n", g_mapTimeSum / (freq.QuadPart / 1000));
-    fprintf(stderr, "Map find RX time sum: %I64dms\n", g_mapFindRXTimeSum / (freq.QuadPart / 1000));
-    fprintf(stderr, "Map create time sum: %I64dms\n", g_mapCreateTimeSum / (freq.QuadPart / 1000));
-    fprintf(stderr, "Unmap time with lock sum: %I64dms\n", g_unmapTimeWithLockSum / (freq.QuadPart / 1000));
-    fprintf(stderr, "Unmap time sum: %I64dms\n", g_unmapTimeSum / (freq.QuadPart / 1000));
-
-    fprintf(stderr, "Reserve count: %I64d\n", g_reserveCount);
-    fprintf(stderr, "Release count: %I64d\n", g_releaseCount);
+    fprintf(stderr, "Map time with lock sum: %lldms\n", g_mapTimeWithLockSum / (freq.QuadPart / 1000));
+    fprintf(stderr, "Map time sum: %lldms\n", g_mapTimeSum / (freq.QuadPart / 1000));
+    fprintf(stderr, "Map find RX time sum: %lldms\n", g_mapFindRXTimeSum / (freq.QuadPart / 1000));
+    fprintf(stderr, "Map create time sum: %lldms\n", g_mapCreateTimeSum / (freq.QuadPart / 1000));
+    fprintf(stderr, "Unmap time with lock sum: %lldms\n", g_unmapTimeWithLockSum / (freq.QuadPart / 1000));
+    fprintf(stderr, "Unmap time sum: %lldms\n", g_unmapTimeSum / (freq.QuadPart / 1000));
+
+    fprintf(stderr, "Reserve count: %lld\n", g_reserveCount);
+    fprintf(stderr, "Release count: %lld\n", g_releaseCount);
 
     fprintf(stderr, "ExecutableWriterHolder usage:\n");
 
diff --git a/src/coreclr/utilcode/loaderheap.cpp b/src/coreclr/utilcode/loaderheap.cpp
index c2514efe39b6ee..56da111506a34d 100644
--- a/src/coreclr/utilcode/loaderheap.cpp
+++ b/src/coreclr/utilcode/loaderheap.cpp
@@ -1997,7 +1997,7 @@ void UnlockedLoaderHeap::DumpFreeList()
                 }
             }
 
-            printf("Addr = %pxh, Size = %lxh", pBlock, ((ULONG)dwsize));
+            printf("Addr = %pxh, Size = %xh", pBlock, ((ULONG)dwsize));
             if (ccbad) printf(" *** ERROR: NOT CC'd ***");
             if (sizeunaligned) printf(" *** ERROR: size not a multiple of ALLOC_ALIGN_CONSTANT ***");
             printf("\n");
diff --git a/src/coreclr/vm/clrex.cpp b/src/coreclr/vm/clrex.cpp
index 645687b28f5c6e..a8440f3f927a86 100644
--- a/src/coreclr/vm/clrex.cpp
+++ b/src/coreclr/vm/clrex.cpp
@@ -1136,8 +1136,8 @@ void EEResourceException::GetMessage(SString &result)
     // since we don't want to call managed code here.
     //
 
-    result.Printf("%s (message resource %S)",
-                  CoreLibBinder::GetExceptionName(m_kind), m_resourceName.GetUnicode());
+    result.Printf("%s (message resource %s)",
+                  CoreLibBinder::GetExceptionName(m_kind), m_resourceName.GetUTF8());
 }
 
 BOOL EEResourceException::GetThrowableMessage(SString &result)
diff --git a/src/coreclr/vm/comutilnative.cpp b/src/coreclr/vm/comutilnative.cpp
index dbe8bc0b7c3bcd..99e51aae7397ea 100644
--- a/src/coreclr/vm/comutilnative.cpp
+++ b/src/coreclr/vm/comutilnative.cpp
@@ -1279,7 +1279,7 @@ void GCInterface::AddMemoryPressure(UINT64 bytesAllocated)
     UINT64 add = m_addPressure[0] + m_addPressure[1] + m_addPressure[2] + m_addPressure[3] - m_addPressure[p];
     UINT64 rem = m_remPressure[0] + m_remPressure[1] + m_remPressure[2] + m_remPressure[3] - m_remPressure[p];
 
-    STRESS_LOG4(LF_GCINFO, LL_INFO10000, "AMP Add: %I64u => added=%I64u total_added=%I64u total_removed=%I64u",
+    STRESS_LOG4(LF_GCINFO, LL_INFO10000, "AMP Add: %llu => added=%llu total_added=%llu total_removed=%llu",
         bytesAllocated, newMemValue, add, rem);
 
     SendEtwAddMemoryPressureEvent(bytesAllocated);
@@ -1321,7 +1321,7 @@ void GCInterface::AddMemoryPressure(UINT64 bytesAllocated)
                 // last check - if we would exceed 20% of GC "duty cycle", do not trigger GC at this time
                 if ((size_t)(pGCHeap->GetNow() - pGCHeap->GetLastGCStartTime(2)) > (pGCHeap->GetLastGCDuration(2) * 5))
                 {
-                    STRESS_LOG6(LF_GCINFO, LL_INFO10000, "AMP Budget: pressure=%I64u ? budget=%I64u (total_added=%I64u, total_removed=%I64u, mng_heap=%I64u) pos=%d",
+                    STRESS_LOG6(LF_GCINFO, LL_INFO10000, "AMP Budget: pressure=%llu ? budget=%llu (total_added=%llu, total_removed=%llu, mng_heap=%llu) pos=%d",
                         newMemValue, budget, add, rem, heapOver3 * 3, m_iteration);
 
                     GarbageCollectModeAny(2);
@@ -1360,7 +1360,7 @@ void GCInterface::RemoveMemoryPressure(UINT64 bytesAllocated)
 
     InterlockedAdd(&m_remPressure[p], bytesAllocated);
 
-    STRESS_LOG2(LF_GCINFO, LL_INFO10000, "AMP Remove: %I64u => removed=%I64u",
+    STRESS_LOG2(LF_GCINFO, LL_INFO10000, "AMP Remove: %llu => removed=%llu",
         bytesAllocated, m_remPressure[p]);
 }
 
diff --git a/src/coreclr/vm/eedbginterfaceimpl.cpp b/src/coreclr/vm/eedbginterfaceimpl.cpp
index 6dfeb8b46f57bb..313f240ede1903 100644
--- a/src/coreclr/vm/eedbginterfaceimpl.cpp
+++ b/src/coreclr/vm/eedbginterfaceimpl.cpp
@@ -1230,7 +1230,7 @@ bool EEDbgInterfaceImpl::TraceFrame(Thread *thread,
         SUPPRESS_ALLOCATION_ASSERTS_IN_THIS_SCOPE;
         FAULT_NOT_FATAL();
         SString buffer;
-        StubManager::DbgWriteLog("  td=%S\n", trace->DbgToString(buffer));
+        StubManager::DbgWriteLog("  td=%s\n", trace->DbgToString(buffer));
     }
     else
     {
@@ -1276,7 +1276,7 @@ bool EEDbgInterfaceImpl::TraceManager(Thread *thread,
         // Should never be on helper thread
         FAULT_NOT_FATAL();
         SString buffer;
-        StubManager::DbgWriteLog("  td=%S\n", trace->DbgToString(buffer));
+        StubManager::DbgWriteLog("  td=%s\n", trace->DbgToString(buffer));
     }
     else
     {
diff --git a/src/coreclr/vm/gcheaputilities.cpp b/src/coreclr/vm/gcheaputilities.cpp
index 817179eb2f017f..a7e96f23573af3 100644
--- a/src/coreclr/vm/gcheaputilities.cpp
+++ b/src/coreclr/vm/gcheaputilities.cpp
@@ -168,8 +168,9 @@ HMODULE LoadStandaloneGc(LPCWSTR libFileName)
     PathString libPath = GetInternalSystemDirectory();
     libPath.Append(libFileName);
 
+    LOG((LF_GC, LL_INFO100, "Loading standalone GC from path %s\n", libPath.GetUTF8()));
+
     LPCWSTR libraryName = libPath.GetUnicode();
-    LOG((LF_GC, LL_INFO100, "Loading standalone GC from path %S\n", libraryName));
     return CLRLoadLibrary(libraryName);
 }
 #endif // FEATURE_STANDALONE_GC
diff --git a/src/coreclr/vm/generics.cpp b/src/coreclr/vm/generics.cpp
index aed942fb78a995..1ccf8128445a1a 100644
--- a/src/coreclr/vm/generics.cpp
+++ b/src/coreclr/vm/generics.cpp
@@ -185,7 +185,7 @@ ClassLoader::CreateTypeHandleForNonCanonicalGenericInstantiation(
     {
         StackSString debugTypeKeyName;
         TypeString::AppendTypeKeyDebug(debugTypeKeyName, pTypeKey);
-        LOG((LF_CLASSLOADER, LL_INFO1000, "GENERICS: New instantiation requested: %S\n", debugTypeKeyName.GetUnicode()));
+        LOG((LF_CLASSLOADER, LL_INFO1000, "GENERICS: New instantiation requested: %s\n", debugTypeKeyName.GetUTF8()));
 
         if (g_pConfig->ShouldBreakOnInstantiation(debugTypeKeyName.GetUTF8()))
             CONSISTENCY_CHECK_MSGF(false, ("BreakOnInstantiation: typename '%s' ", debugTypeKeyName.GetUTF8()));
diff --git a/src/coreclr/vm/genmeth.cpp b/src/coreclr/vm/genmeth.cpp
index da38d13e1d624e..44f99a84c24fe7 100644
--- a/src/coreclr/vm/genmeth.cpp
+++ b/src/coreclr/vm/genmeth.cpp
@@ -380,8 +380,8 @@ InstantiatedMethodDesc::NewInstantiatedMethodDesc(MethodTable *pExactMT,
                     TypeString::AppendMethodDebug(name, pGenericMDescInRepMT);
                     DWORD dictionarySlotSize;
                     DWORD dictionaryAllocSize = DictionaryLayout::GetDictionarySizeFromLayout(pGenericMDescInRepMT->GetNumGenericMethodArgs(), pDL, &dictionarySlotSize);
-                    LOG((LF_JIT, LL_INFO1000, "GENERICS: Created new dictionary layout for dictionary of slot size %d / alloc size %d for %S\n",
-                        dictionarySlotSize, dictionaryAllocSize, name.GetUnicode()));
+                    LOG((LF_JIT, LL_INFO1000, "GENERICS: Created new dictionary layout for dictionary of slot size %d / alloc size %d for %s\n",
+                        dictionarySlotSize, dictionaryAllocSize, name.GetUTF8()));
                 }
 #endif // _DEBUG
             }
diff --git a/src/coreclr/vm/ildump.h b/src/coreclr/vm/ildump.h
index 86a028355bde8f..c3e1b4ab842759 100644
--- a/src/coreclr/vm/ildump.h
+++ b/src/coreclr/vm/ildump.h
@@ -37,9 +37,9 @@ IL_OPCODE(0x1d,             "ldc.i4.7       ", 0, ILDUMP_VOID, "", 0)
 IL_OPCODE(0x1e,             "ldc.i4.8       ", 0, ILDUMP_VOID, "", 0)
 IL_OPCODE(0x1f,             "ldc.i4.s       ", 1, BYTE, "%d", 0)
 IL_OPCODE(0x20,             "ldc.i4         ", 4, UNALIGNED INT32, "0x%08x", 0)
-IL_OPCODE(0x21,             "ldc.i8         ", 8, UNALIGNED INT64, "0x%I64x", 0)
+IL_OPCODE(0x21,             "ldc.i8         ", 8, UNALIGNED INT64, "0x%llx", 0)
 IL_OPCODE(0x22,             "ldc.r4         ", 4, UNALIGNED INT32, "0x%08x", 0)
-IL_OPCODE(0x23,             "ldc.r8         ", 8, UNALIGNED INT64, "0x%I64x", 0)
+IL_OPCODE(0x23,             "ldc.r8         ", 8, UNALIGNED INT64, "0x%llx", 0)
 IL_OPCODE(0x25,             "dup            ", 0, ILDUMP_VOID, "", 0)
 IL_OPCODE(0x26,             "pop            ", 0, ILDUMP_VOID, "", 0)
 IL_OPCODE(0x27,             "jmp            ", 4, UNALIGNED INT32, "0x%08x", 0)
diff --git a/src/coreclr/vm/jitinterface.cpp b/src/coreclr/vm/jitinterface.cpp
index 9c8d9cbe59c0b5..64bbc15f8e99e0 100644
--- a/src/coreclr/vm/jitinterface.cpp
+++ b/src/coreclr/vm/jitinterface.cpp
@@ -8174,15 +8174,15 @@ void CEEInfo::reportInliningDecision (CORINFO_METHOD_HANDLE inlinerHnd,
         if (dontInline(inlineResult))
         {
             LOG((LF_JIT, LL_INFO100000,
-                 "While compiling '%S', inline of '%S' into '%S' failed because: '%s'.\n",
-                 currentMethodName.GetUnicode(), inlineeMethodName.GetUnicode(),
-                 inlinerMethodName.GetUnicode(), reason));
+                 "While compiling '%s', inline of '%s' into '%s' failed because: '%s'.\n",
+                 currentMethodName.GetUTF8(), inlineeMethodName.GetUTF8(),
+                 inlinerMethodName.GetUTF8(), reason));
         }
         else if(inlineResult == INLINE_PASS)
         {
-            LOG((LF_JIT, LL_INFO100000, "While compiling '%S', inline of '%S' into '%S' succeeded.\n",
-                 currentMethodName.GetUnicode(), inlineeMethodName.GetUnicode(),
-                 inlinerMethodName.GetUnicode()));
+            LOG((LF_JIT, LL_INFO100000, "While compiling '%s', inline of '%s' into '%s' succeeded.\n",
+                 currentMethodName.GetUTF8(), inlineeMethodName.GetUTF8(),
+                 inlinerMethodName.GetUTF8()));
 
         }
     }
@@ -8419,9 +8419,9 @@ void CEEInfo::reportTailCallDecision (CORINFO_METHOD_HANDLE callerHnd,
         if (tailCallResult == TAILCALL_FAIL)
         {
             LOG((LF_JIT, LL_INFO100000,
-                 "While compiling '%S', %Splicit tail call from '%S' to '%S' failed because: '%s'.\n",
-                 currentMethodName.GetUnicode(), fIsTailPrefix ? W("ex") : W("im"),
-                 callerMethodName.GetUnicode(), calleeMethodName.GetUnicode(), reason));
+                 "While compiling '%s', %splicit tail call from '%s' to '%s' failed because: '%s'.\n",
+                 currentMethodName.GetUTF8(), fIsTailPrefix ? "ex" : "im",
+                 callerMethodName.GetUTF8(), calleeMethodName.GetUTF8(), reason));
         }
         else
         {
@@ -8430,9 +8430,9 @@ void CEEInfo::reportTailCallDecision (CORINFO_METHOD_HANDLE callerHnd,
             };
             _ASSERTE(tailCallResult >= 0 && (size_t)tailCallResult < ARRAY_SIZE(tailCallType));
             LOG((LF_JIT, LL_INFO100000,
-                 "While compiling '%S', %Splicit tail call from '%S' to '%S' generated as a %s.\n",
-                 currentMethodName.GetUnicode(), fIsTailPrefix ? W("ex") : W("im"),
-                 callerMethodName.GetUnicode(), calleeMethodName.GetUnicode(), tailCallType[tailCallResult]));
+                 "While compiling '%s', %splicit tail call from '%s' to '%s' generated as a %s.\n",
+                 currentMethodName.GetUTF8(), fIsTailPrefix ? "ex" : "im",
+                 callerMethodName.GetUTF8(), calleeMethodName.GetUTF8(), tailCallType[tailCallResult]));
 
         }
     }
@@ -13098,7 +13098,7 @@ PCODE UnsafeJitFunction(PrepareCodeConfig* config,
         if (LoggingOn(LF_JIT, LL_INFO10000))
             TypeString::AppendMethodDebug(methodString, ftn);
 
-        LOG((LF_JIT, LL_INFO10000, "{ Jitting method (%p) %S %s\n", ftn, methodString.GetUnicode(), ftn->m_pszDebugMethodSignature));
+        LOG((LF_JIT, LL_INFO10000, "{ Jitting method (%p) %s %s\n", ftn, methodString.GetUTF8(), ftn->m_pszDebugMethodSignature));
     }
 
 #if 0
@@ -13133,7 +13133,7 @@ PCODE UnsafeJitFunction(PrepareCodeConfig* config,
         if (LoggingOn(LF_VERIFIER, LL_INFO100))
             TypeString::AppendMethodDebug(methodString, ftn);
 
-        LOG((LF_VERIFIER, LL_INFO100, "{ Will verify method (%p) %S %s\n", ftn, methodString.GetUnicode(), ftn->m_pszDebugMethodSignature));
+        LOG((LF_VERIFIER, LL_INFO100, "{ Will verify method (%p) %s %s\n", ftn, methodString.GetUTF8(), ftn->m_pszDebugMethodSignature));
     }
 #endif //_DEBUG
 
diff --git a/src/coreclr/vm/methodtable.cpp b/src/coreclr/vm/methodtable.cpp
index d42d4e3efc1453..aee002516bda24 100644
--- a/src/coreclr/vm/methodtable.cpp
+++ b/src/coreclr/vm/methodtable.cpp
@@ -4771,7 +4771,7 @@ void MethodTable::DoFullyLoad(Generics::RecursionGraph * const pVisited,  const
     {
         SString name;
         TypeString::AppendTypeDebug(name, this);
-        LOG((LF_CLASSLOADER, LL_INFO10000, "PHASEDLOAD: Completed full dependency load of type %S\n", name.GetUnicode()));
+        LOG((LF_CLASSLOADER, LL_INFO10000, "PHASEDLOAD: Completed full dependency load of type %s\n", name.GetUTF8()));
     }
 #endif
 
diff --git a/src/coreclr/vm/methodtablebuilder.cpp b/src/coreclr/vm/methodtablebuilder.cpp
index be4fee76f2f3f3..0adbf52d386553 100644
--- a/src/coreclr/vm/methodtablebuilder.cpp
+++ b/src/coreclr/vm/methodtablebuilder.cpp
@@ -1355,10 +1355,10 @@ MethodTableBuilder::BuildMethodTableThrowing(
         pszDebugName = (LPCUTF8)name;
     }
 
-    LOG((LF_CLASSLOADER, LL_INFO1000, "Loading class \"%s%s%S\" from module \"%ws\" in domain 0x%p %s\n",
+    LOG((LF_CLASSLOADER, LL_INFO1000, "Loading class \"%s%s%s\" from module \"%ws\" in domain 0x%p %s\n",
         *pszDebugNamespace ? pszDebugNamespace : "",
         *pszDebugNamespace ? NAMESPACE_SEPARATOR_STR : "",
-        debugName.GetUnicode(),
+        debugName.GetUTF8(),
         pModule->GetDebugName(),
         pModule->GetDomain(),
         (pModule->IsSystem()) ? "System Domain" : ""
diff --git a/src/coreclr/vm/multicorejit.cpp b/src/coreclr/vm/multicorejit.cpp
index 754d4e9297696a..3526ef15c7bb6d 100644
--- a/src/coreclr/vm/multicorejit.cpp
+++ b/src/coreclr/vm/multicorejit.cpp
@@ -155,7 +155,7 @@ HRESULT MulticoreJitRecorder::WriteOutput()
     {
         CFileStream fileStream;
 
-        if (SUCCEEDED(hr = fileStream.OpenForWrite(m_fullFileName)))
+        if (SUCCEEDED(hr = fileStream.OpenForWrite(m_fullFileName.GetUnicode())))
         {
             hr = WriteOutput(& fileStream);
         }
diff --git a/src/coreclr/vm/nativeimage.cpp b/src/coreclr/vm/nativeimage.cpp
index 1bfd266164bcaf..0844ca510f314f 100644
--- a/src/coreclr/vm/nativeimage.cpp
+++ b/src/coreclr/vm/nativeimage.cpp
@@ -67,7 +67,7 @@ void NativeImage::Initialize(READYTORUN_HEADER *pHeader, LoaderAllocator *pLoade
     m_pReadyToRunInfo = new ReadyToRunInfo(/*pModule*/ NULL, pLoaderAllocator, m_pImageLayout, pHeader, this, pamTracker);
     m_pComponentAssemblies = m_pReadyToRunInfo->FindSection(ReadyToRunSectionType::ComponentAssemblies);
     m_componentAssemblyCount = m_pComponentAssemblies->Size / sizeof(READYTORUN_COMPONENT_ASSEMBLIES_ENTRY);
-    
+
     // Check if the current module's image has native manifest metadata, otherwise the current->GetNativeAssemblyImport() asserts.
     m_pManifestMetadata = LoadManifestMetadata();
 
@@ -82,12 +82,12 @@ void NativeImage::Initialize(READYTORUN_HEADER *pHeader, LoaderAllocator *pLoade
         m_assemblySimpleNameToIndexMap.Add(AssemblyNameIndex(assemblyName, m_manifestAssemblyCount));
         m_manifestAssemblyCount++;
     }
-    
+
     // When a composite image contributes to a larger version bubble, its manifest assembly
     // count may exceed its component assembly count as it may contain references to
     // assemblies outside of the composite image that are part of its version bubble.
     _ASSERTE(m_manifestAssemblyCount >= m_componentAssemblyCount);
-    
+
     S_SIZE_T dwAllocSize = S_SIZE_T(sizeof(PTR_Assembly)) * S_SIZE_T(m_manifestAssemblyCount);
 
     // Note: Memory allocated on loader heap is zero filled
@@ -195,7 +195,7 @@ NativeImage *NativeImage::Open(
 
                 fullPath.Append(DIRECTORY_SEPARATOR_CHAR_W);
                 fullPath += compositeImageFileName;
-                
+
                 EX_TRY
                 {
                     peLoadedImage = PEImageLayout::LoadNative(fullPath);
@@ -212,9 +212,9 @@ NativeImage *NativeImage::Open(
         if (peLoadedImage.IsNull())
         {
             // Failed to locate the native composite R2R image
-            LOG((LF_LOADER, LL_ALWAYS, "LOADER: failed to load native image '%s' for component assembly '%S' using search paths: '%S'\n",
+            LOG((LF_LOADER, LL_ALWAYS, "LOADER: failed to load native image '%s' for component assembly '%s' using search paths: '%S'\n",
                 nativeImageFileName,
-                path.GetUnicode(),
+                path.GetUTF8(),
                 searchPathsConfig != nullptr ? searchPathsConfig : W("<use COMPlus_NativeImageSearchPaths to set>")));
             RaiseFailFastException(nullptr, nullptr, 0);
         }
diff --git a/src/coreclr/vm/pendingload.cpp b/src/coreclr/vm/pendingload.cpp
index 1bc384befab56c..ddfad3fb792a12 100644
--- a/src/coreclr/vm/pendingload.cpp
+++ b/src/coreclr/vm/pendingload.cpp
@@ -217,7 +217,7 @@ void PendingTypeLoadTable::Dump()
             SString name;
             TypeKey entryTypeKey = pSearch->pData->GetTypeKey();
             TypeString::AppendTypeKeyDebug(name, &entryTypeKey);
-            LOG((LF_CLASSLOADER, LL_INFO10000, "  Entry %S with handle %p at level %s\n", name.GetUnicode(), pSearch->pData->m_typeHandle.AsPtr(),
+            LOG((LF_CLASSLOADER, LL_INFO10000, "  Entry %s with handle %p at level %s\n", name.GetUTF8(), pSearch->pData->m_typeHandle.AsPtr(),
                  pSearch->pData->m_typeHandle.IsNull() ? "not-applicable" : classLoadLevelName[pSearch->pData->m_typeHandle.GetLoadLevel()]));
         }
     }
diff --git a/src/coreclr/vm/perfinfo.cpp b/src/coreclr/vm/perfinfo.cpp
index 85e44ac8668dac..0452f413f41d11 100644
--- a/src/coreclr/vm/perfinfo.cpp
+++ b/src/coreclr/vm/perfinfo.cpp
@@ -22,12 +22,12 @@ PerfInfo::PerfInfo(int pid)
     }
 
     SString path;
-    path.Printf("%Sperfinfo-%d.map", tempPath.GetUnicode(), pid);
+    path.Printf("%sperfinfo-%d.map", tempPath.GetUTF8(), pid);
     OpenFile(path);
 }
 
 // Logs image loads into the process' perfinfo-%d.map file
-void PerfInfo::LogImage(PEAssembly* pPEAssembly, WCHAR* guid)
+void PerfInfo::LogImage(PEAssembly* pPEAssembly, CHAR* guid)
 {
     CONTRACTL
     {
@@ -55,7 +55,7 @@ void PerfInfo::LogImage(PEAssembly* pPEAssembly, WCHAR* guid)
         }
     }
 
-    value.Printf("%S%c%S%c%p", path.GetUnicode(), sDelimiter, guid, sDelimiter, baseAddr);
+    value.Printf("%s%c%s%c%p", path.GetUTF8(), sDelimiter, guid, sDelimiter, baseAddr);
 
     SString command;
     command.Printf("%s", "ImageLoad");
@@ -80,8 +80,8 @@ void PerfInfo::WriteLine(SString& type, SString& value)
     }
 
     SString line;
-    line.Printf("%S%c%S%c\n",
-            type.GetUnicode(), sDelimiter, value.GetUnicode(), sDelimiter);
+    line.Printf("%s%c%s%c\n",
+            type.GetUTF8(), sDelimiter, value.GetUTF8(), sDelimiter);
 
     EX_TRY
     {
diff --git a/src/coreclr/vm/perfinfo.h b/src/coreclr/vm/perfinfo.h
index 16b06865925c64..02624008af66f3 100644
--- a/src/coreclr/vm/perfinfo.h
+++ b/src/coreclr/vm/perfinfo.h
@@ -22,7 +22,7 @@ class PerfInfo {
 public:
     PerfInfo(int pid);
     ~PerfInfo();
-    void LogImage(PEAssembly* pPEAssembly, WCHAR* guid);
+    void LogImage(PEAssembly* pPEAssembly, CHAR* guid);
 
 private:
     CFileStream* m_Stream;
diff --git a/src/coreclr/vm/perfmap.cpp b/src/coreclr/vm/perfmap.cpp
index 62872b67e42377..b68cffad7bc73d 100644
--- a/src/coreclr/vm/perfmap.cpp
+++ b/src/coreclr/vm/perfmap.cpp
@@ -244,10 +244,10 @@ void PerfMap::LogImage(PEAssembly * pPEAssembly)
 
     EX_TRY
     {
-        WCHAR wszSignature[39];
-        GetNativeImageSignature(pPEAssembly, wszSignature, ARRAY_SIZE(wszSignature));
+        CHAR szSignature[GUID_STR_BUFFER_LEN];
+        GetNativeImageSignature(pPEAssembly, szSignature, ARRAY_SIZE(szSignature));
 
-        m_PerfInfo->LogImage(pPEAssembly, wszSignature);
+        m_PerfInfo->LogImage(pPEAssembly, szSignature);
     }
     EX_CATCH{} EX_END_CATCH(SwallowAllExceptions);
 }
@@ -356,21 +356,21 @@ void PerfMap::LogStubs(const char* stubType, const char* stubOwner, PCODE pCode,
     EX_CATCH{} EX_END_CATCH(SwallowAllExceptions);
 }
 
-void PerfMap::GetNativeImageSignature(PEAssembly * pPEAssembly, WCHAR * pwszSig, unsigned int nSigSize)
+void PerfMap::GetNativeImageSignature(PEAssembly * pPEAssembly, CHAR * pszSig, unsigned int nSigSize)
 {
     CONTRACTL{
         PRECONDITION(pPEAssembly != nullptr);
-        PRECONDITION(pwszSig != nullptr);
-        PRECONDITION(nSigSize >= 39);
+        PRECONDITION(pszSig != nullptr);
+        PRECONDITION(nSigSize >= GUID_STR_BUFFER_LEN);
     } CONTRACTL_END;
 
     // We use the MVID as the signature, since ready to run images
     // don't have a native image signature.
     GUID mvid;
     pPEAssembly->GetMVID(&mvid);
-    if(!GuidToLPWSTR(mvid, pwszSig, nSigSize))
+    if(!GuidToLPSTR(mvid, pszSig, nSigSize))
     {
-        pwszSig[0] = '\0';
+        pszSig[0] = '\0';
     }
 }
 
@@ -387,13 +387,13 @@ NativeImagePerfMap::NativeImagePerfMap(Assembly * pAssembly, BSTR pDestPath)
 
     // Get the native image signature (GUID).
     // Used to ensure that we match symbols to the correct NGEN image.
-    WCHAR wszSignature[39];
-    GetNativeImageSignature(pAssembly->GetPEAssembly(), wszSignature, ARRAY_SIZE(wszSignature));
+    CHAR szSignature[GUID_STR_BUFFER_LEN];
+    GetNativeImageSignature(pAssembly->GetPEAssembly(), szSignature, ARRAY_SIZE(szSignature));
 
     // Build the path to the perfmap file, which consists of <inputpath><imagesimplename>.ni.<signature>.map.
     // Example: /tmp/System.Private.CoreLib.ni.{GUID}.map
     SString sDestPerfMapPath;
-    sDestPerfMapPath.Printf("%S%s.ni.%S.map", pDestPath, lpcSimpleName, wszSignature);
+    sDestPerfMapPath.Printf("%S%s.ni.%s.map", pDestPath, lpcSimpleName, szSignature);
 
     // Open the perf map file.
     OpenFile(sDestPerfMapPath);
diff --git a/src/coreclr/vm/perfmap.h b/src/coreclr/vm/perfmap.h
index 587a776e682760..b04568341ecab4 100644
--- a/src/coreclr/vm/perfmap.h
+++ b/src/coreclr/vm/perfmap.h
@@ -60,7 +60,7 @@ class PerfMap
     void LogImage(PEAssembly * pPEAssembly);
 
     // Get the image signature and store it as a string.
-    static void GetNativeImageSignature(PEAssembly * pPEAssembly, WCHAR * pwszSig, unsigned int nSigSize);
+    static void GetNativeImageSignature(PEAssembly * pPEAssembly, CHAR * pszSig, unsigned int nSigSize);
 
 public:
     // Initialize the map for the current process.
diff --git a/src/coreclr/vm/qcall.h b/src/coreclr/vm/qcall.h
index ab5e4b4cb2b2ef..c8c890f438831e 100644
--- a/src/coreclr/vm/qcall.h
+++ b/src/coreclr/vm/qcall.h
@@ -95,7 +95,7 @@
 //          COMPlusThrow(kArgumentException, L"InvalidFlags");
 //
 //      // No need to worry about GC moving strings passed into QCall. Marshaling pins them for us.
-//      printf("%S", wszString);
+//      wprintf("%s", wszString);
 //
 //      // This is the most efficient way to return strings back to managed code. No need to use StringBuilder.
 //      retString.Set(L"Hello");
diff --git a/src/coreclr/vm/readytoruninfo.cpp b/src/coreclr/vm/readytoruninfo.cpp
index 2284a9f0e7d456..aad72b92ef1e22 100644
--- a/src/coreclr/vm/readytoruninfo.cpp
+++ b/src/coreclr/vm/readytoruninfo.cpp
@@ -429,7 +429,7 @@ static void LogR2r(const char *msg, PEAssembly *pPEAssembly)
     if (r2rLogFile == NULL)
         return;
 
-    fprintf(r2rLogFile, "%s: \"%S\".\n", msg, pPEAssembly->GetPath().GetUnicode());
+    fprintf(r2rLogFile, "%s: \"%s\".\n", msg, pPEAssembly->GetPath().GetUTF8());
     fflush(r2rLogFile);
 }
 
diff --git a/src/coreclr/vm/stublink.cpp b/src/coreclr/vm/stublink.cpp
index 7111f83653583f..58048bfb1ab8c2 100644
--- a/src/coreclr/vm/stublink.cpp
+++ b/src/coreclr/vm/stublink.cpp
@@ -2465,15 +2465,15 @@ VOID ArgBasedStubCache::Dump()
     CONTRACTL_END;
 
     printf("--------------------------------------------------------------\n");
-    printf("ArgBasedStubCache dump (%lu fixed entries):\n", m_numFixedSlots);
+    printf("ArgBasedStubCache dump (%u fixed entries):\n", m_numFixedSlots);
     for (UINT32 i = 0; i < m_numFixedSlots; i++) {
 
-        printf("  Fixed slot %lu: ", (ULONG)i);
+        printf("  Fixed slot %u: ", (ULONG)i);
         Stub *pStub = m_aStub[i];
         if (!pStub) {
             printf("empty\n");
         } else {
-            printf("%zxh   - refcount is %lu\n",
+            printf("%zxh   - refcount is %u\n",
                    (size_t)(pStub->GetEntryPoint()),
                    (ULONG)( *( ( ((ULONG*)(pStub->GetEntryPoint())) - 1))));
         }
@@ -2483,9 +2483,9 @@ VOID ArgBasedStubCache::Dump()
          pSlotEntry != NULL;
          pSlotEntry = pSlotEntry->m_pNext) {
 
-        printf("  Dyna. slot %lu: ", (ULONG)(pSlotEntry->m_key));
+        printf("  Dyna. slot %u: ", (ULONG)(pSlotEntry->m_key));
         Stub *pStub = pSlotEntry->m_pStub;
-        printf("%zxh   - refcount is %lu\n",
+        printf("%zxh   - refcount is %u\n",
                (size_t)(pStub->GetEntryPoint()),
                (ULONG)( *( ( ((ULONG*)(pStub->GetEntryPoint())) - 1))));
 
diff --git a/src/coreclr/vm/stubmgr.cpp b/src/coreclr/vm/stubmgr.cpp
index 94bc431533055c..fcf9838e9e2355 100644
--- a/src/coreclr/vm/stubmgr.cpp
+++ b/src/coreclr/vm/stubmgr.cpp
@@ -53,7 +53,7 @@ void LogTraceDestination(const char * szHint, PCODE stubAddr, TraceDestination *
 #ifdef _DEBUG
 // Get a string representation of this TraceDestination
 // Uses the supplied buffer to store the memory (or may return a string literal).
-const WCHAR * TraceDestination::DbgToString(SString & buffer)
+const CHAR * TraceDestination::DbgToString(SString & buffer)
 {
     CONTRACTL
     {
@@ -63,12 +63,12 @@ const WCHAR * TraceDestination::DbgToString(SString & buffer)
     }
     CONTRACTL_END;
 
-    const WCHAR * pValue = W("unknown");
+    const CHAR * pValue = "unknown";
 
 #ifndef DACCESS_COMPILE
     if (!StubManager::IsStubLoggingEnabled())
     {
-        return W("<unavailable while native-debugging>");
+        return "<unavailable while native-debugging>";
     }
     // Now that we know we're not interop-debugging, we can safely call new.
     SUPPRESS_ALLOCATION_ASSERTS_IN_THIS_SCOPE;
@@ -82,50 +82,50 @@ const WCHAR * TraceDestination::DbgToString(SString & buffer)
         {
             case TRACE_ENTRY_STUB:
                 buffer.Printf("TRACE_ENTRY_STUB(addr=0x%p)", GetAddress());
-                pValue = buffer.GetUnicode();
+                pValue = buffer.GetUTF8();
                 break;
 
             case TRACE_STUB:
                 buffer.Printf("TRACE_STUB(addr=0x%p)", GetAddress());
-                pValue = buffer.GetUnicode();
+                pValue = buffer.GetUTF8();
                 break;
 
             case TRACE_UNMANAGED:
                 buffer.Printf("TRACE_UNMANAGED(addr=0x%p)", GetAddress());
-                pValue = buffer.GetUnicode();
+                pValue = buffer.GetUTF8();
                 break;
 
             case TRACE_MANAGED:
                 buffer.Printf("TRACE_MANAGED(addr=0x%p)", GetAddress());
-                pValue = buffer.GetUnicode();
+                pValue = buffer.GetUTF8();
                 break;
 
             case TRACE_UNJITTED_METHOD:
             {
                 MethodDesc * md = this->GetMethodDesc();
                 buffer.Printf("TRACE_UNJITTED_METHOD(md=0x%p, %s::%s)", md, md->m_pszDebugClassName, md->m_pszDebugMethodName);
-                pValue = buffer.GetUnicode();
+                pValue = buffer.GetUTF8();
             }
                 break;
 
             case TRACE_FRAME_PUSH:
                 buffer.Printf("TRACE_FRAME_PUSH(addr=0x%p)", GetAddress());
-                pValue = buffer.GetUnicode();
+                pValue = buffer.GetUTF8();
                 break;
 
             case TRACE_MGR_PUSH:
                 buffer.Printf("TRACE_MGR_PUSH(addr=0x%p, sm=%s)", GetAddress(), this->GetStubManager()->DbgGetName());
-                pValue = buffer.GetUnicode();
+                pValue = buffer.GetUTF8();
                 break;
 
             case TRACE_OTHER:
-                pValue = W("TRACE_OTHER");
+                pValue = "TRACE_OTHER";
                 break;
         }
     }
     EX_CATCH
     {
-        pValue = W("(OOM while printing TD)");
+        pValue = "(OOM while printing TD)";
     }
     EX_END_CATCH(SwallowAllExceptions);
 #endif
@@ -542,7 +542,7 @@ BOOL StubManager::TraceStub(PCODE stubStartAddress, TraceDestination *trace)
                 SUPPRESS_ALLOCATION_ASSERTS_IN_THIS_SCOPE;
                 FAULT_NOT_FATAL();
                 SString buffer;
-                DbgWriteLog("  td=%S\n", trace->DbgToString(buffer));
+                DbgWriteLog("  td=%s\n", trace->DbgToString(buffer));
             }
             else
             {
diff --git a/src/coreclr/vm/stubmgr.h b/src/coreclr/vm/stubmgr.h
index 719db338443627..49e2e837704765 100644
--- a/src/coreclr/vm/stubmgr.h
+++ b/src/coreclr/vm/stubmgr.h
@@ -86,7 +86,7 @@ class TraceDestination
     // Get a string representation of this TraceDestination
     // Uses the supplied buffer to store the memory (or may return a string literal).
     // This will also print the TD's arguments.
-    const WCHAR * DbgToString(SString &buffer);
+    const CHAR * DbgToString(SString &buffer);
 #endif
 
     // Initialize for unmanaged code.
diff --git a/src/coreclr/vm/typehandle.cpp b/src/coreclr/vm/typehandle.cpp
index 88dce11a4fc172..e3834add43d654 100644
--- a/src/coreclr/vm/typehandle.cpp
+++ b/src/coreclr/vm/typehandle.cpp
@@ -1561,50 +1561,50 @@ CHECK TypeHandle::CheckMatchesKey(TypeKey *pKey) const
         {
             MethodTable *pMT = AsMethodTable();
             CHECK_MSGF(pMT->GetInternalCorElementType() == pKey->GetKind(),
-                       ("CorElementType %d of Array MethodTable does not match key %S", pMT->GetArrayElementType(), typeKeyString.GetUnicode()));
+                       ("CorElementType %d of Array MethodTable does not match key %s", pMT->GetArrayElementType(), typeKeyString.GetUTF8()));
 
             CHECK_MSGF(pMT->GetArrayElementTypeHandle() == pKey->GetElementType(),
-                       ("Element type of Array MethodTable does not match key %S",typeKeyString.GetUnicode()));
+                       ("Element type of Array MethodTable does not match key %s",typeKeyString.GetUTF8()));
 
             CHECK_MSGF(pMT->GetRank() == pKey->GetRank(),
-                       ("Rank %d of Array MethodTable does not match key %S", pMT->GetRank(), typeKeyString.GetUnicode()));
+                       ("Rank %d of Array MethodTable does not match key %s", pMT->GetRank(), typeKeyString.GetUTF8()));
         }
         else
         if (IsTypeDesc())
         {
             TypeDesc *pTD = AsTypeDesc();
             CHECK_MSGF(pTD->GetInternalCorElementType() == pKey->GetKind(),
-                       ("CorElementType %d of TypeDesc does not match key %S", pTD->GetInternalCorElementType(), typeKeyString.GetUnicode()));
+                       ("CorElementType %d of TypeDesc does not match key %s", pTD->GetInternalCorElementType(), typeKeyString.GetUTF8()));
 
             if (CorTypeInfo::IsModifier(pKey->GetKind()))
             {
                 CHECK_MSGF(pTD->GetTypeParam() == pKey->GetElementType(),
-                           ("Element type of TypeDesc does not match key %S",typeKeyString.GetUnicode()));
+                           ("Element type of TypeDesc does not match key %s",typeKeyString.GetUTF8()));
             }
         }
         else
         {
             MethodTable *pMT = AsMethodTable();
-            CHECK_MSGF(pMT->GetModule() == pKey->GetModule(), ("Module of MethodTable does not match key %S", typeKeyString.GetUnicode()));
+            CHECK_MSGF(pMT->GetModule() == pKey->GetModule(), ("Module of MethodTable does not match key %s", typeKeyString.GetUTF8()));
             CHECK_MSGF(pMT->GetCl() == pKey->GetTypeToken(),
-                       ("TypeDef %x of Methodtable does not match TypeDef %x of key %S", pMT->GetCl(), pKey->GetTypeToken(),
-                        typeKeyString.GetUnicode()));
+                       ("TypeDef %x of Methodtable does not match TypeDef %x of key %s", pMT->GetCl(), pKey->GetTypeToken(),
+                        typeKeyString.GetUTF8()));
 
             if (pMT->IsTypicalTypeDefinition())
             {
                 CHECK_MSGF(pKey->GetNumGenericArgs() == 0 && !pKey->HasInstantiation(),
-                           ("Key %S for Typical MethodTable has non-zero number of generic arguments", typeKeyString.GetUnicode()));
+                           ("Key %s for Typical MethodTable has non-zero number of generic arguments", typeKeyString.GetUTF8()));
             }
             else
             {
                 CHECK_MSGF(pMT->GetNumGenericArgs() == pKey->GetNumGenericArgs(),
-                           ("Number of generic params %d in MethodTable does not match key %S", pMT->GetNumGenericArgs(), typeKeyString.GetUnicode()));
+                           ("Number of generic params %d in MethodTable does not match key %s", pMT->GetNumGenericArgs(), typeKeyString.GetUTF8()));
                 if (pKey->HasInstantiation())
                 {
                     for (DWORD i = 0; i < pMT->GetNumGenericArgs(); i++)
                     {
                         CHECK_MSGF(pMT->GetInstantiation()[i] == pKey->GetInstantiation()[i],
-                               ("Generic argument %d in MethodTable does not match key %S", i, typeKeyString.GetUnicode()));
+                               ("Generic argument %d in MethodTable does not match key %s", i, typeKeyString.GetUTF8()));
                     }
                 }
             }
diff --git a/src/mono/dlls/dbgshim/dbgshim.cpp b/src/mono/dlls/dbgshim/dbgshim.cpp
index 255626f9ee49aa..8140f1f0525589 100644
--- a/src/mono/dlls/dbgshim/dbgshim.cpp
+++ b/src/mono/dlls/dbgshim/dbgshim.cpp
@@ -191,21 +191,6 @@ HRESULT CreateCoreDbg(HMODULE hDBIModule, DWORD processId, int iDebuggerVersion,
     return hr;
 }
 
-char* convertC(const WCHAR * wString)
-{
-    int size;
-    char * MultiBuffer = NULL;
-
-    size = WideCharToMultiByte(CP_ACP,0,wString,-1,MultiBuffer,0,NULL,NULL);
-    MultiBuffer = (char*) malloc(size);
-    if (MultiBuffer == NULL)
-    {
-        return NULL;
-    }
-    WideCharToMultiByte(CP_ACP,0,wString,-1,MultiBuffer,size,NULL,NULL);
-    return MultiBuffer;
-}
-
 static IUnknown* pCordb = NULL;
 
 MONO_API HRESULT
diff --git a/src/mono/mono/utils/mono-mmap-windows.c b/src/mono/mono/utils/mono-mmap-windows.c
index 034e44aa006093..7f04666b4a4230 100644
--- a/src/mono/mono/utils/mono-mmap-windows.c
+++ b/src/mono/mono/utils/mono-mmap-windows.c
@@ -250,7 +250,7 @@ mono_file_map_error (size_t length, int flags, int fd, guint64 offset, void **re
 			CloseHandle (mapping);
 		if (error_message) {
 			gchar *win32_error_string = format_win32_error_string (win32_error);
-			*error_message = g_strdup_printf ("%s failed file:%s length:0x%IX offset:0x%I64X function:%s error:%s(0x%X)\n",
+			*error_message = g_strdup_printf ("%s failed file:%s length:0x%zX offset:0x%llX function:%s error:%s(0x%X)\n",
 				__func__, filepath ? filepath : "", length, offset, failed_function, win32_error_string, win32_error);
 			g_free (win32_error_string);
 		}