[Bug] Anthropic API Error: Cannot modify thinking blocks in assistant message
Resolved 💬 1 comment Opened May 29, 2026 by mdwitr0 Closed Jul 2, 2026
Bug Description
API Error: 400 messages.1.content.4: 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: vscode
- Version: 2.1.154
- Feedback ID: 10a96613-6310-40ed-8eb6-5d4cf7d2e0fd
Errors
[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.1.content.4: `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_011CbX7MvGP8Tuf8ejWSdoSj\"}\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":"2026-05-29T15:38:49.134Z"}]This issue has 1 comment on GitHub. Read the full discussion on GitHub ↗