API Error 400: Could not process image (recurring)

Bug Report

Error

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"},"request_id":"req_011CY6XM33vgu4KWQkribnbS"}

Description

Any screenshot/image added to the conversation triggers a 400 invalid_request_error with message "Could not process image", regardless of file type. Once the error occurs, every subsequent message in the conversation also fails with the same error, making the session completely unusable. The only workaround is to /clear and start over, losing all conversation context.

This is a recurring, reproducible issue.

Steps to Reproduce

1. Start a Claude Code CLI session
2. Add/paste any screenshot or image (any file type — PNG, JPG, etc.)
3. Error 400: Could not process image appears
4. Every subsequent message in the same session also returns the same error
5. Only way to recover is /clear, which loses all context

Expected Behavior

• Images/screenshots should be processed without error
• A single failed image should not poison the entire conversation session

Impact

• Severity: High — completely blocks image-based workflows and forces loss of conversation context
• Cannot use screenshots for debugging, UI review, or any visual context
• Forces full context reset via /clear

Environment

• Platform: macOS (Darwin 25.2.0)
• Model: Claude Opus 4.6
• File types tested: All common image formats (PNG, JPG, etc.) — all fail

Request ID

req_011CY6XM33vgu4KWQkribnbS