431 Request Header Fields Too Large

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This error response indicates the server refused the request due to a header that is too long. Usually, the request can be completed after reducing the header size.

This error can also be caused by an issue with cookies or if the referrer URL is too long.

The user should clear their cache and cookies and review the request. If possible try requesting without using a referral URL.

If the issue persists then contact the server support for help.

The HTTP 431 Request Header Fields Too Large response status code indicates that the server refuses to process the request because the request’s HTTP headers are too long. The request may be resubmitted after reducing the size of the request headers.

431 can be used when the total size of request headers is too large, or when a single header field is too large. To help those running into this error, indicate which of the two is the problem in the response body — ideally, also include which headers are too large. This lets users attempt to fix the problem, such as by clearing their cookies.

Servers will often produce this status if:

  • The Referer URL is too long
  • There are too many Cookies sent in the request


431 Request Header Fields Too Large


RFC 6585, section 5: 431 Request Header Fields Too LargeAdditional HTTP Status Codes