DevToolsmith

HTTP 422 Unprocessable Content

HTTP 422 Unprocessable Content means the request is well-formed, but its contents fail validation. The request contains an error or can’t be fulfilled. Retrying unchanged won’t help.

Class
4xx Client error
Standard
RFC 9110
Cacheable by default
No
Safe to retry
No
Go constant
http.StatusUnprocessableEntity

What HTTP 422 means

The JSON parsed fine, but the data is invalid: an email without @, an end date before the start date, a missing required field. FastAPI, Rails and Laravel return 422 for validation errors by default. 400 is the alternative when the body can’t even be parsed.

How to fix a 422 error

  • Read the response body. Frameworks list each invalid field, e.g. FastAPI’s detail array with loc and msg.

Retrying

No. Fix the request first; sending it again unchanged will get the same response.

Example response

HTTP/1.1 422 Unprocessable Content
Date: Wed, 21 Oct 2026 10:30:00 GMT
Content-Type: application/json

How to return 422

Node.js (Express)
res.status(422).json({ error: 'Unprocessable Content' });
Python (FastAPI)
from fastapi import HTTPException

raise HTTPException(status_code=422, detail="Unprocessable Content")
Go (net/http)
http.Error(w, http.StatusText(http.StatusUnprocessableEntity), http.StatusUnprocessableEntity)
nginx
location /private/ {
    return 422;
}

Related status codes

Other 4xx status codes

400 Bad Request · 401 Unauthorized · 402 Payment Required · 403 Forbidden · 404 Not Found · 405 Method Not Allowed · 406 Not Acceptable · 407 Proxy Authentication Required · 408 Request Timeout · 409 Conflict · 410 Gone · 411 Length Required · 412 Precondition Failed · 413 Content Too Large · 414 URI Too Long · 415 Unsupported Media Type · 416 Range Not Satisfiable · 417 Expectation Failed · 418 I’m a Teapot · 421 Misdirected Request · 423 Locked · 424 Failed Dependency · 425 Too Early · 426 Upgrade Required · 428 Precondition Required · 429 Too Many Requests · 431 Request Header Fields Too Large · 444 No Response · 451 Unavailable For Legal Reasons · 499 Client Closed Request

See the full list of HTTP status codes.

Sources

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Frequently asked questions

What does HTTP 422 Unprocessable Content mean?

HTTP 422 Unprocessable Content means the request is well-formed, but its contents fail validation. The JSON parsed fine, but the data is invalid: an email without @, an end date before the start date, a missing required field. FastAPI, Rails and Laravel return 422 for validation errors by default. 400 is the alternative when the body can’t even be parsed.

How do I fix HTTP 422?

Read the response body. Frameworks list each invalid field, e.g. FastAPI’s detail array with loc and msg.