Quick answer
HTTP status code 431 (Request Header Fields Too Large) means: The request headers, often the cookies, are too large. Yes, a client error: the request was wrong or not allowed. Usually the link, the login or the data sent needs to change.
Is it an error?
4xx Client errors
Yes, a client error: the request was wrong or not allowed. Usually the link, the login or the data sent needs to change.
Common causes
- Cookies or headers too large
If you are visiting the site
- Clear the browser's cache and cookies for this site
If you run the website
- Reduce cookie size or raise header size limits
Frequently asked questions
What does HTTP 431 mean?
HTTP status code 431 (Request Header Fields Too Large) means: The request headers, often the cookies, are too large.
Is HTTP 431 an error?
Yes, a client error: the request was wrong or not allowed. Usually the link, the login or the data sent needs to change.
How do I fix a 431 error?
If you are visiting the site: Clear the browser's cache and cookies for this site. If you run the website: Reduce cookie size or raise header size limits.
4xx Client errors
HTTP 400 Bad RequestThe server cannot process the request because it is malformed or invalid.HTTP 401 UnauthorizedYou need to log in: authentication is required and was missing or invalid.HTTP 403 ForbiddenThe server understood the request but refuses to give access.HTTP 404 Not FoundThe server cannot find the requested page or file.HTTP 405 Method Not AllowedThe request method (for example POST) is not allowed for this URL.HTTP 406 Not AcceptableThe server cannot return the content in a format the client said it accepts.HTTP 407 Proxy Authentication RequiredYou must first sign in to the proxy server between you and the website.HTTP 408 Request TimeoutThe server waited too long for the client to finish sending the request.HTTP 409 ConflictThe request conflicts with the current state of the resource.