[Bug] Anthropic API Error: Cannot modify thinking blocks in assistant message
Resolved 💬 1 comment Opened May 29, 2026 by dalex160 Closed Jul 1, 2026
Bug Description
API Error: 400 messages.3.content.24: 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: iTerm.app
- Version: 2.1.154
- Feedback ID: 5c099af1-a8aa-4f1e-b2d3-5ff922382567
Errors
[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.3.content.24: `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_011CbViBRV48aHxVvC6S96SF\"}\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":"2026-05-28T21:54:14.189Z"}]This issue has 1 comment on GitHub. Read the full discussion on GitHub ↗