[Bug] Anthropic API Error: Cannot modify thinking blocks in assistant messages
Resolved 💬 2 comments Opened May 28, 2026 by evanrichards Closed Jun 1, 2026
Bug Description
⎿ API Error: 400 messages.23.content.10: thinking or redacted_thinking blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original
response.
Environment Info
- Platform: darwin
- Terminal: tmux
- Version: 2.1.154
- Feedback ID: 124f5ef6-bb62-42f7-b747-df174af2cc71
Errors
[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.23.content.10: `thinking` or `redacted_thinking` blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response.\"},\"request_id\":\"req_011CbVW6TTLRudRLSobj4cVN\"}\n at generate (/$bunfs/root/src/entrypoints/cli.js:11:63816)\n at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T19:15:45.072Z"}]This issue has 2 comments on GitHub. Read the full discussion on GitHub ↗