[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?

When trying to code or doing a task this presented:
API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.99: all messages must have non-empty
content except for the optional final assistant message"},"request_id":"req_011CXZH3wa48pKjxxXSGSteg"}

What Should Happen?

Not that.

Error Messages/Logs

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.99: all messages must have non-empty
    content except for the optional final assistant message"},"request_id":"req_011CXZH3wa48pKjxxXSGSteg"}

Steps to Reproduce

Write a prompt
Get the message

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.20

Claude Code Version

2.1.21

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

_No response_