The server cannot process the request because of malformed syntax or invalid framing.
Quick facts
When does it occur
The server cannot process the request because of malformed syntax or invalid framing.
It belongs to the 4xx Client Error class of responses, defined in RFC7231#6.5.1.
Browse all codes in this class: 4xx Client Error
How to fix it
Validate the request line, headers and body; check JSON/XML syntax and character encoding.
Common causes
How to fix it
Double-check the URL, return to the homepage and search again, or retry later.
Validate the request line, headers and body; check JSON/XML syntax and character encoding.
Review access logs and permission rules for the affected path, and confirm routing and security policies.
Frequently asked questions
400 belongs to the 4xx Client Error class and is generally not cached for long; behavior is controlled by Cache-Control.
4xx Client Error: The server cannot process the request because of malformed syntax or invalid framing.
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 400, 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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