[BUG] API Error : 400

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?

i keep getting this error while using Claude Code in the desktop app on Windows. I have been getting this on multiple different systems. I then have to start a new instance. API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.5.content.8: thinking or redacted_thinking blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response."},"request_id":"req_011CX5ZBMXQn6rAfqnAXCV91"}

What Should Happen?

Should work as advertised

Error Messages/Logs

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.5.content.8: thinking or redacted_thinking blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response."},"request_id":"req_011CX5ZBMXQn6rAfqnAXCV91"}

Steps to Reproduce

it's happening after random text inputs

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.0.734

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

claude.ai-web.log