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[BUG] This model does not support assistant message prefill. The conversation must end with a user message. #36

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Description

@auloin

What happened?

When using the chat, there is sometimes a com.anthropic.errors.BadRequestException: 400 exception (see below relevant logs). This happens when using Claude AI's API.

I don't know the exact steps to reproduce this but after reaching this state, new messages are ignored but instead the last successful user message in the chat is repeated (in the chat history).

Relevant logs

com.anthropic.errors.BadRequestException: 400: {type=error, error={type=invalid_request_error, message=This model does not support assistant message prefill. The conversation must end with a user message.}

Activity

  1. rdehuyss commented on Mar 30, 2026

    @rdehuyss
    Collaborator

    Can you check again as #41 might have solved it?

  2. added 2 commits that reference this issue on Apr 10, 2026
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