431 Request Header Fields Too Large
The HTTP 431 Request Header Fields Too Large
client error 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 clients running into this error, indicate which of the two is the problem in the response body and, ideally, say which headers are too large. This lets people attempt to fix the problem, such as by clearing cookies.
Servers will often produce this status if:
Status
431 Request Header Fields Too Large
Examples
Header field too large
In the following example, the Cookie
header is too large in the request:
GET /doc HTTP/1.1
Host: example.com
Cookie: cookie1=value1; cookie2=value2; cookie3=[…]
The server responds with an message indicating which header was problematic:
HTTP/1.1 431 Request Header Fields Too Large
Content-Type: text/html
<!doctype html>
<head>
<title>Request Header Fields Too Large</title>
</head>
<body>
<h1>Request Header Fields Too Large</h1>
<p>The "Cookie" header was too large.</p>
</body>
</html>
Specifications
Specification |
---|
RFC 6585 # section-5 |