Dispatch: 400 error - text content blocks must contain non-whitespace text

Description

Dispatch consistently returns a 400 API error on every message sent:

API Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages: text content blocks must contain non-whitespace text"},"request_id":"req_011CZrTqSGP4NPm4tJcpi9g9"}

Steps to reproduce

1. Open Dispatch in the Claude desktop app
2. Send any message (e.g. "hello?")
3. Error appears immediately — every subsequent message also fails with the same error

What I've tried

• Restarting the Dispatch session
• Creating a new task
• Clearing the conversation
• Fully quitting and restarting the Claude desktop app
• Attempting to update the app via Homebrew (app was installed via .dmg, not brew)

None of these resolved the issue. The error persists across all new Dispatch sessions.

Environment

• macOS (Darwin 25.4.0, Apple Silicon)
• Claude desktop app (Max plan)
• Was working on a project ("traceless" — Expo/React Native app) when it stopped working

Analysis

The API error indicates that the Dispatch client is sending a message with an empty or whitespace-only text content block in the messages array. This may be caused by a corrupted/empty assistant message in the conversation history being resent with each new request.

🤖 Generated with Claude Code