What it means
The request is well-formed but contains semantic errors, so the server cannot process it. Formerly Unprocessable Entity.
Common causes
- Validation failed (invalid email, missing required field)
- Business rule violated
- Rails or Laravel validation errors
How to fix it
As a client or visitor
Read the field errors in the body, fix the values and resubmit.
As the site or API owner
Return machine-readable field errors so forms can highlight them.
Example response
HTTP/1.1
HTTP/1.1 422 Unprocessable Content
Date: Tue, 07 Oct 2025 09:30:00 GMT
Server: nginx
Content-Type: application/problem+json
{
"type": "about:blank",
"title": "Unprocessable Content",
"status": 422,
"errors": [
{
"field": "email",
"message": "must be a valid email address"
}
]
}Specification
FAQ
› Should validation errors use 400 or 422?
Many APIs use 422 for validation and 400 for unparseable input. Either is valid; be consistent.
› Is 422 only for WebDAV?
It started in WebDAV but RFC 9110 now defines it for general HTTP.