HTTP 422 Unprocessable Content
What a 422 Unprocessable Content response means, why it happens, and the fastest ways to fix it.
The request is syntactically valid but semantically wrong — well-formed JSON whose values fail validation (missing required field, bad enum value, invalid email).
- Validation failures in REST frameworks (Rails, FastAPI, NestJS default).
- GitHub-style APIs rejecting logically invalid input.
- Read the response body — validation errors are usually itemized per field.
- Match types and required fields against the API schema exactly.
Notes
HTTP status codes are defined in RFC 9110 (which replaced RFC 7231). The first digit is the class: 1xx informational, 2xx success, 3xx redirection, 4xx client error, 5xx server error.
Same class: 400 · 401 · 403 · 404 · 405 · 408 · 409 · 410 · 412 · 413 · 415 · 418 · 425 · 429 · 431 · 451
All codes: HTTP status code reference
Frequently asked questions
What does HTTP 422 mean?
HTTP 422 Unprocessable Content: The request is syntactically valid but semantically wrong — well-formed JSON whose values fail validation (missing required field, bad enum value, invalid email).
How do I fix a 422 error?
Read the response body — validation errors are usually itemized per field. Match types and required fields against the API schema exactly.
Is a 422 my fault or the server's?
422 is a client error — the request itself needs to change, though server misconfiguration can also trigger it.