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claude-code - 💡(How to fix) Fix [Bug] Anthropic API Error: Invalid thinking block format

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Error Message

[{"error":"Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.3.content.8: 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_011CbVUVUJavi5ZaGCWAAYJL"}\n at generate (/$bunfs/root/src/entrypoints/cli.js:11:63571)\n at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T18:54:43.570Z"},{"error":"Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.3.content.8: 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_011CbVUbKbdbGgmpf1b9iCwM"}\n at generate (/$bunfs/root/src/entrypoints/cli.js:11:63571)\n at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T18:56:02.940Z"}]

Code Example

[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.3.content.8: `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_011CbVUVUJavi5ZaGCWAAYJL\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63571)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T18:54:43.570Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.3.content.8: `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_011CbVUbKbdbGgmpf1b9iCwM\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63571)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T18:56:02.940Z"}]
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Bug Description thinking blocks errors.

Environment Info

  • Platform: linux
  • Terminal: cursor
  • Version: 2.1.154
  • Feedback ID: 2c0e1ab6-cb56-46a3-b0b5-f4556d5e7b9d

Errors

[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.3.content.8: `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_011CbVUVUJavi5ZaGCWAAYJL\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63571)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T18:54:43.570Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.3.content.8: `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_011CbVUbKbdbGgmpf1b9iCwM\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63571)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T18:56:02.940Z"}]

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