Claude Sonnet 4 thinks it hasnt created a file

Bug Reports
1

Since the latest updates, Claude Sonnet 4 will hallucinate that it hasnt created a file and keep trying to create it until I tell it that it has

This is happening on all newly created files currently

Replication steps:

  1. Issue a prompt that will create a new file, any file

Behaviour:

  • Agent will create the file, then say something like “It seems the file doesn’t exist yet. Let me create it:” and try to create it again.

Version: 1.0.0
OS: Windows_NT x64 10.0.26100

2

it may only be happening for larger files (> 600 or so lines)

3

Hey, could you let me know if this is happening in a relatively new chat? If it’s occurring in a long-running chat, that might explain it — the model may be starting to hallucinate.

If this is happening in a new chat, it would be helpful if you could share the request ID. To do that, first disable privacy mode, then try to reproduce the issue, copy the request ID, and send it here.

4

Sorry this is happening on a business account with privacy mode enabled at a team level so I cant provide a request ID. However it does seem to be happening on longer running chats. New chats seem to perform a lot better so far, Ill keep an eye on it and report back if I see it again on a new chat.

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