The request headers are larger than the server can handle.
Quick facts
When does it occur
The request headers are larger than the server can handle.
It belongs to the 4xx Client Error class of responses, defined in RFC6585#5.
Browse all codes in this class: 4xx Client Error
How to fix it
Reduce cookies and custom headers, or raise the server header-size limit.
Common causes
How to fix it
Double-check the URL, return to the homepage and search again, or retry later.
Reduce cookies and custom headers, or raise the server header-size limit.
Review access logs and permission rules for the affected path, and confirm routing and security policies.
Frequently asked questions
431 belongs to the 4xx Client Error class and is generally not cached for long; behavior is controlled by Cache-Control.
4xx Client Error: The request headers are larger than the server can handle.
Sources & standards
Updated 2026-09-13
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about this tool
This page provides original, human-reviewed information about HTTP status codes such as 431, the HTTP Status Code Reference and related concepts. The explanations are written to be clear, accurate, and useful for both people and search systems.
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