[Bug] Anthropic API Error: thinking blocks in assistant message cannot be modified
Resolved 💬 3 comments Opened May 29, 2026 by schiste Closed Jul 3, 2026
Bug Description
⎿ API Error: 400 messages.3.content.76: thinking or redacted_thinking blocks in the latest assistant message cannot be modified.
These blocks must remain as they were in the original response. > no explaination of the root cause
Environment Info
- Platform: darwin
- Terminal: Chau7
- Version: 2.1.154
- Feedback ID: d10ac0d0-cf8a-463f-a7b1-f72d11681170
Errors
[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.3.content.76: `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_011CbVcQP9KcjRAb2h66j44f\"}\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":"2026-05-28T20:38:29.377Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.3.content.76: `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_011CbVcn9CYa3shme98oJ75o\"}\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":"2026-05-28T20:43:24.511Z"}]This issue has 3 comments on GitHub. Read the full discussion on GitHub ↗