Articles/HTTP

HTTP 400 Bad Request — What It Means

What HTTP status code 400 Bad Request means, when servers return it, and how to handle it correctly.

Published September 23, 2026

HTTP 400 Bad Request — The server couldn't understand the request due to invalid syntax.

Key points

  • Means the request itself is malformed — invalid JSON, missing required fields in the structure, or bad headers
  • Distinct from 422, which means the syntax was fine but the data failed validation rules
  • Check the raw request body and headers for structural errors before assuming a validation bug
More HTTP articles