[BUG] API Error: 400 The request body is not valid JSON: str is not valid UTF-8: surrogates not allowed: line 1 column 1 (char 0)

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 I am trying to attach and image both PNG and JPEG to the chat . Throwing this error API Error: 400 The request body is not valid JSON: str is not valid UTF-8: surrogates not allowed: line 1 column 1 (char 0)

What Should Happen?

Claude should parse the image and take action

Error Messages/Logs

Steps to Reproduce

NA

Claude Model

None

Is this a regression?

No, this never worked

Last Working Version

_No response_

Claude Code Version

Claude Code v2.1.178

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_