HTTP 400 Bad Request

HTTP 400 Bad Request indicates a client errors response outcome.

What this status code means

Bad Request describes how the server processed the request and what the client should do next.

Who should act first

Client request or identity context is usually the first place to fix.

What to check first

Capture exact request path, method, and headers.
Verify authentication and authorization context.
Validate payload schema and content type.

How it differs from similar codes

HTTP 401 Unauthorized — full guide

Reference and next step

Specification: RFC 9110.

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