[BUG] Dispatch: 400 "Could not process image" on every message

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?

Every message sent through the built-in Dispatch feature in the Claude Code desktop app immediately fails with a 400 invalid_request_error, even when the user sends a plain text message with no image attached.

Error returned:

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"},"request_id":"req_011CaGGRAt4hSGwSWo5erD2R"}

The error mentions "image" even though no image was attached, which suggests Dispatch is internally attaching some asset that the API cannot process.

Reproduces 100% of the time — not intermittent. Regular (non-Dispatch) Claude Code sessions work normally on the same machine.

What Should Happen?

Dispatch should process plain text messages normally (as a regular Claude Code session does) without attempting to attach images when the user hasn't provided any.

Error Messages/Logs

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"},"request_id":"req_011CaGGRAt4hSGwSWo5erD2R"}

Steps to Reproduce

1. Open Claude Code desktop app on Windows
2. Click "Dispatch" in the left sidebar to open the built-in Dispatch view
3. Type any plain text message (e.g. "hello") and send it — no image or file attached
4. The response fails immediately with the 400 error shown above
5. Every subsequent message produces the same error — reproduces 100% of the time

Note: This feature worked previously. The 400 error started occurring on or before 2026-04-19 and has persisted since.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.114 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

• The error is not intermittent — every single Dispatch message fails with the same 400.
• Regular Claude Code CLI sessions on the same machine work normally, so the issue appears specific to the Dispatch feature.
• The error message mentions "image" despite no image being sent by the user, suggesting Dispatch may be auto-attaching an asset (screenshot, context blob, etc.) that the API cannot process.
• First observed: on or before 2026-04-19. Still reproducing as of 2026-04-21 (no changes on user side).
• No screenshots attached intentionally, to avoid leaking unrelated workspace content. Happy to provide redacted ones on request.