431 Request Header Fields Too Large
The 431 HTTP response status code is returned by the server to indicate that the request’s headers are too large.
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Introduction
In Action
Sample
Conclusion
Introduction
The HTTP response status code 431 Request Header Fields Too Large is returned by the server to indicate that the request’s headers are too large. It can mean that the total size of all headers combined is too big or that specific headers themselves are too large.
This status code helps prevent issues where excessive header data could impact server performance or lead to potential security vulnerabilities.
In Action
When you encounter the 431 Request Header Fields Too Large status code, it means that the server is unable to process your HTTP request because there is an excessive amount of data in the HTTP headers. This could be either the total size of all headers combined or specific ones causing the issue.
To resolve this, you can try removing some unnecessary HTTP headers from your request, and one common approach is to reduce the size of Cookies being transmitted. Keep in mind that this status code may prevent search engines from indexing URLs with this response, so it’s essential to address the issue for proper website functioning.
Sample
In the example, when the client sends a request to access a resource, the server returns the 431 Request Header Fields Too Large status code.
This happens because the total size of two large cookie values in the request exceeds the maximum limit set by the server for HTTP headers. To resolve this, the client can try removing or reducing the size of these cookies in the subsequent request to stay within the server’s header size limit.
Request
GET /tech-news HTTP/1.1
Host: www.example.com
Cookie: first_cookie=< very_long>; second_cookie=< long again!>
Response
HTTP/1.1 431 Request Header Fields Too Large
Content-Type: text/html
Content-Length: 183
< html>
< head>
< title>Request Headers Too Long< /title>
< /head>
< body>
< p>Your request headers are too long. Try retrying the request without cookies.< /p>
< /body>
< /html>
Conclusion
The 431 Request Header Fields Too Large status code is returned by the server when the HTTP headers in the client’s request are too large, either due to the total size of all headers or specific ones. To fix this issue, the client can try removing or reducing the size of cookies or other headers in the request to meet the server’s header size limit.
