[BUG] Claude Dispatch returns "Could not process image" error (400 invalid_request_error) on every message, breaking sessions on Windows

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?

Description

When using Claude Dispatch (remote control from phone) on Windows 11 (Claude Desktop from Microsoft Store), every message sent to the AI returns a raw API error that completely breaks the session.

Actual Behavior

Each message returns the following error as raw text in the Dispatch chat:

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"},"request_id":"req_01ICY6XM33vgu4KWQkribnbS"}

The error appears on every single message, even when no image is being sent at all. The same request_id is returned across all messages, indicating the session state is corrupted on the server side.

It is no longer possible to send any messages from Dispatch at all — the entire interface is blocked by this error. Dispatch is completely unusable until a new session is create
It is no longer possible to send any messages from Dispatch at all - the entire interface is completely blocked by this error message. Dispatch is entirely unusable until the session is reset.d.

What Should Happen?

When sending a message via Claude Dispatch, the AI should respond normally. If an image processing error occurs, it should:

1. Return a proper error message instead of raw JSON/API response text
2. Not permanently brick the session - users should be able to continue after a single error
3. Recover gracefully from a failed image processing attempt without corrupting the session state for subsequent messages

The request_id should reset between sessions, and text-only messages should not return invalid_request_error responses after an image processing failure.

Error Messages/Logs

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"Could not process image"},"request_id":"req_01ICY6XM33vgu4KWQkribnbS"}

Steps to Reproduce

NOTE: Exact reproduction steps are not known. The issue appears to be triggered by a specific workflow in Claude Cowork/Dispatch.

1. Open Claude Cowork on Windows 11
2. Connect Claude Dispatch from a phone
3. Use Dispatch to ask Claude to access/consult documents (via the local file system)
4. At some point during document access, an image processing error occurs on the server side
5. After this error, every subsequent message in the Dispatch session returns a raw API error (400 invalid_request_error)

The exact trigger for the initial image processing error is unknown. It may occur when Claude processes documents that contain images or during file indexing.

Important: The bug is intermittent and may depend on the specific documents being accessed or their format.

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.160

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Windows Terminal

Additional Information

Note: This bug specifically affects Claude Desktop app (not CLI). The user installed Claude Desktop from Microsoft Store on Windows 11. Claude Dispatch is accessed from a mobile phone (iOS/Android) to remotely control the Claude Desktop session.

The error appears to be related to image processing in Claude Cowork/Dispatch when accessing the local file system. It may be related to document indexing or image preview generation on the server side.

Workaround: Starting a new session resolves the issue temporarily, but it can recur when using Dispatch to browse documents again.