opencode web mode broken: empty page - multiple versions and multiple os

[sciabarracom]

Description

I installed opencode using web ui with opencode web, I get a blank page with this error in console:

:49956/assets/index-BRXIaEVp.js:1 Failed to load module script: Expected a JavaScript-or-Wasm module script but the server responded with a MIME type of "text/html". Strict MIME type checking is enforced for module scripts per HTML spec.

executing curl http://localhost::49956/assets/index-BRXIaEVp.js returns the index.html not the javascript

OpenCode version

1.0.134 1.0.133 1.0.132 1.0.131

Steps to reproduce

I installed opencode on both linux and mac various versions - same problem everywhere - the crazy thing this yesterday worked file.

I am puzzled.

Screenshot and/or share link

Operating System

mac os 15.16.1, ubuntu 24.04

Terminal

iterm, gnome-terminal

[thetaungg]

I'm facing the exact same problem

[thetaungg]

I found the reason.
It's because https://desktop.dev.opencode.ai is down.
Every opencode version is pointing to that server to get the static assets for the website and the server and index-BRXIaEVp.js file doesn't exist there anymore.

I'm not sure why opencode is doing that instead of locally building desktop with each version.

If you update the proxy to desktop.opencode.ai in this file and rebuild the binary, it should work

packages/opencode/src/server/server.ts

 .all("/*", async (c) => {
        return proxy(`https://desktop.opencode.ai${c.req.path}`, {
          ...c.req,
          headers: {
            host: "desktop.opencode.ai",
          },
        })

I haven't tried to build the desktop locally and including it in the binary. But we should be able to do that as well

[adamdotdevin]

this should be fixed now, lmk if you see it again

[adamdotdevin]

Closing, the issue here was that the server was sometimes cached and not using latest version.

[imjeehoo]

I see this on 1.0.194
Loading module from “http://127.0.0.1:4096/assets/index-CFCjwJ3H.js” was blocked because of a disallowed MIME type (“text/html”).

[sourman]

looks like something else is causing the same symptoms at least. Seeing this now. TUI works fine. opencode web gives me blank. JavaScript files are apparently marked incorrect MIME type by the proxy

[sourman]

I submitted #6113 to hopefully fix this? not sure what other issues might be linked

[tomzx]

I'm still observing this as of 1.0.2211.0.222 when trying to reach http://localhost:10000.

Failed to load module script: Expected a JavaScript-or-Wasm module script but the server responded with a MIME type of "". Strict MIME type checking is enforced for module scripts per HTML spec.

[sourman]

@tomzx confirmed

[sourman]

investigated a bunch and found that the _headers file I added in #6113 exists in packages/app/public/_headers and is copied to dist/_headers during build
For some reason Cloudflare Pages is serving _headers as a static asset instead of reading it as configuration

Since JavaScript files are missing the Content-Type: application/javascript header browsers refuse to run the javascript

I have not found any Cloudflare Pages announced incident regarding this. Really not sure why Cloudflare would stop parsing the _headers file properly

[sourman]

EDIT Jan 4 2026:
No longer needed. issue is fixed in prod

---

I created a local temp workaround if anyone is running into this
you can git clone and then bun build a new binary which will modify the MIME type correctly which then allows the browser to run the JS https://github.com/sourman/opencode/tree/fix/cloudflare-mime-type-workaround