400

Bad Request

Client Error

RFC 7231

Popular

The server cannot or will not process the request due to something that is perceived to be a client error.

Detailed Information

The 400 status code indicates that the server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).

Common Examples

Invalid syntax
Missing required fields
Invalid data formats

Common Uses

API requests with invalid input
Form submissions with errors
Invalid requests to web pages

Best Practices

Validate client input server-side
Provide helpful error messages
Use appropriate response body structure

Quick Actions

Category Information

Client Error

The request contains bad syntax or cannot be fulfilled

Related Status Codes

3 similar

401

Unauthorized

The request requires user authentication.

402

Payment Required

Reserved for future use.

403

Forbidden

The server understood the request, but is refusing to fulfill it.

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