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HTTP 431 Request Header Fields Too Large

Headers exceed the server's size limits — often a runaway cookie or oversized auth token.

4xx · Client error✗ not retryable — fix the request instead

Fix checklist

  • Strip unnecessary cookies from API requests.
  • Check for headers accidentally accumulating values.

Spec: RFC reference

Related status codes

400 Bad Request

The server cannot process the request due to a client error — malformed JSON, invalid parameters, or schema violations..

401 Unauthorized

Authentication is missing or invalid for this request..

402 Payment Required

The request requires payment — billing is not set up or a balance is exhausted..

403 Forbidden

The server understood the request but refuses to authorize it — valid credentials, insufficient permission..

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