[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?

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.11.content.0.type:
Expected thinking or redacted_thinking, but found text. When thinking is enabled, a final assistant
message must start with a thinking block (preceeding the lastmost set of tool_use and tool_result blocks). We
recommend you include thinking blocks from previous turns. To avoid this requirement, disable thinking. Please
consult our documentation at
https://docs.claude.com/en/docs/build-with-claude/extended-thinking"},"request_id":"req_011CXTQEEFyCPGnrEPNhaQu8"}

What Should Happen?

Expectation is to run the code without this error

Error Messages/Logs

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.11.content.0.type:
    Expected `thinking` or `redacted_thinking`, but found `text`. When `thinking` is enabled, a final `assistant`
    message must start with a thinking block (preceeding the lastmost set of `tool_use` and `tool_result` blocks). We
    recommend you include thinking blocks from previous turns. To avoid this requirement, disable `thinking`. Please
    consult our documentation at
    https://docs.claude.com/en/docs/build-with-claude/extended-thinking"},"request_id":"req_011CXTQEEFyCPGnrEPNhaQu8"}

Steps to Reproduce

I dont know, I just started to run code and this keeps happening

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.19

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

PowerShell

Additional Information

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.11.content.0.type:
Expected thinking or redacted_thinking, but found text. When thinking is enabled, a final assistant
message must start with a thinking block (preceeding the lastmost set of tool_use and tool_result blocks). We
recommend you include thinking blocks from previous turns. To avoid this requirement, disable thinking. Please
consult our documentation at
https://docs.claude.com/en/docs/build-with-claude/extended-thinking"},"request_id":"req_011CXTQEEFyCPGnrEPNhaQu8"}