[BUG] VSCode Diagnostics makes CC throw 400 errors
Status Fixed / completed
Maintainer reply ✓ Yes — hackyon-anthropic
Activity 7 comments · opened Oct 13, 2025 · closed Oct 20, 2025
💡 Likely answer: A maintainer (hackyon-anthropic, collaborator)
responded on this thread — see the highlighted reply below.
Preflight Checklist
- [x] I have searched existing issues and this hasn't been reported yet
- [x] This is a single bug report (please file separate reports for different bugs)
- [x] I am using the latest version of Claude Code
What's Wrong?
Sometimes the VSCode Diagnostics tool corrupts the message history and makes Claude Code throw 400 error
What Should Happen?
VSCode Diagnostics should not malform requests to Anthropic
Error Messages/Logs
API Error: 400 due to tool use concurrency issues. Run /rewind to recover the conversation.Steps to Reproduce
- Trigger VSCode Diagnostics
- See error
API Error: 400 due to tool use concurrency issues. Run /rewind to recover the conversation.
Claude Model
Sonnet (default)
Is this a regression?
Yes, this worked in a previous version
Last Working Version
_No response_
Claude Code Version
2.0.13
Platform
Anthropic API
Operating System
macOS
Terminal/Shell
VS Code integrated terminal
Additional Information
_No response_
7 Comments
Found 3 possible duplicate issues:
This issue will be automatically closed as a duplicate in 3 days.
🤖 Generated with Claude Code
Same here; the DiagnosticsVSCode Problems -> is causing API Error: 400 due to tool use concurrency issues. Run /rewind to recover the conversation.
Any chance you can please provide a screenshot here for it?
How did you
Trigger VSCode Diagnostics? Are you using the new VSCode extension UX or the terminal CLI one?It is the VS Code Extension. The Diagnostics are triggered automatically it seems:
<img width="1108" height="570" alt="Image" src="https://github.com/user-attachments/assets/e319c433-73c8-4ee9-81e2-9184f6485622" />
We added a change that should mitigate this. Please let me know if this is still happening for you!
@hackyon-anthropic seems to work fine, even with convos that previously threw 400 errors. Thank you 🙏
This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.