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claude-code - 💡(How to fix) Fix [Bug] Anthropic API Error: 'thinking' blocks cannot be modified [1 pull requests]

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Error Message

[{"error":"Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.27.content.127: 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_011CbVQCMkFfQ74fQYmJ6r73"}\n at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:24.291Z"},{"error":"Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.27.content.127: 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_011CbVQDdfjtVdBEiGnmbEjM"}\n at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:41.450Z"},{"error":"Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.27.content.127: 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_011CbVQDzd4jrFVamBNkFifo"}\n at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:46.368Z"},{"error":"Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.27.content.127: 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_011CbVQEwXKADVX4qeRbkQVA"}\n at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:59.859Z"}]

Fix Action

Fixed

Code Example

[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.27.content.127: `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_011CbVQCMkFfQ74fQYmJ6r73\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:24.291Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.27.content.127: `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_011CbVQDdfjtVdBEiGnmbEjM\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:41.450Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.27.content.127: `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_011CbVQDzd4jrFVamBNkFifo\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:46.368Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.27.content.127: `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_011CbVQEwXKADVX4qeRbkQVA\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:59.859Z"}]
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Bug Description The agent got stuck in an error state while working on test cases for a relatively minor feature (tracking time zone settings from a client in a cloud REST api)

Environment Info

  • Platform: darwin
  • Terminal: Apple_Terminal
  • Version: 2.1.153
  • Feedback ID: 7491ca00-4e23-4ad5-8bca-099d84546c58

Errors

[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.27.content.127: `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_011CbVQCMkFfQ74fQYmJ6r73\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:24.291Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.27.content.127: `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_011CbVQDdfjtVdBEiGnmbEjM\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:41.450Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.27.content.127: `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_011CbVQDzd4jrFVamBNkFifo\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:46.368Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.27.content.127: `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_011CbVQEwXKADVX4qeRbkQVA\"}\n    at generate (/$bunfs/root/src/entrypoints/cli.js:11:63764)\n    at makeRequest (/$bunfs/root/src/entrypoints/cli.js:51:7694)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-05-28T17:58:59.859Z"}]

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