HTTP 431 Request Header Fields Too Large — What It Means & How to Fix It
Error4xx client error
Overview
The HTTP 431 Request Header Fields Too Large status code indicates the server refuses the request because the HTTP headers are too large.
Key Details
- This status code is defined in RFC 6585.
- It can be triggered by a single header that is too large or by the total size of all headers.
- Common when cookies grow too large or too many cookies are set.
- The client should reduce the size of request headers and retry.
Common Causes
- Too many cookies are being sent with the request.
- Individual cookies have grown very large.
- Custom headers contain excessive data.
- Authentication tokens in headers are unusually large.
Steps
- 1Clear cookies for the affected domain and retry.
- 2Review and reduce the number and size of cookies.
- 3Move large data from headers to the request body.
- 4If the problem is a large authentication token, investigate why it is so large.
- 5Increase server header size limits if the headers are legitimately needed.
Tags
httpclient-errorheaderscookiessize-limit
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ErrorFrequently Asked Questions
It means the request headers (including cookies) are too large for the server to process. Clear cookies or reduce header sizes.