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claude-code - 💡(How to fix) Fix [Bug] Anthropic API Error: Cannot modify thinking or redacted_thinking blocks in assistant message

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Error Message

[{"error":"Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.5.content.3: 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_011CbWZEEL8Qmbt746TzhA2f"}\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":"2026-05-29T08:37:26.602Z"},{"error":"Error: 400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.5.content.3: 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_011CbWZH6LFK1ixwbKteqLvp"}\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":"2026-05-29T08:38:05.423Z"}]

Code Example

[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.5.content.3: `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_011CbWZEEL8Qmbt746TzhA2f\"}\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":"2026-05-29T08:37:26.602Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.5.content.3: `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_011CbWZH6LFK1ixwbKteqLvp\"}\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":"2026-05-29T08:38:05.423Z"}]
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Bug Description I'm getting thinkingorredacted_thinking blocks in the latest assistant message cannot be modified. These blocks must remain as they were in the original response. in my session.

Environment Info

  • Platform: linux
  • Terminal: ghostty
  • Version: 2.1.154
  • Feedback ID: a324dcae-658d-459d-a59a-11876cc16ff3

Errors

[{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.5.content.3: `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_011CbWZEEL8Qmbt746TzhA2f\"}\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":"2026-05-29T08:37:26.602Z"},{"error":"Error: 400 {\"type\":\"error\",\"error\":{\"type\":\"invalid_request_error\",\"message\":\"messages.5.content.3: `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_011CbWZH6LFK1ixwbKteqLvp\"}\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":"2026-05-29T08:38:05.423Z"}]

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claude-code - 💡(How to fix) Fix [Bug] Anthropic API Error: Cannot modify thinking or redacted_thinking blocks in assistant message