Why is 422 sometimes called Unprocessable Entity?
WebDAV (RFC 4918) originally named it Unprocessable Entity. RFC 9110 adopted the code for general HTTP in 2022 and renamed it Unprocessable Content.
HTTP 422 UNPROCESSABLE CONTENT
The syntax is fine but the content fails validation. Common in JSON APIs. 422 belongs to the 4xx client error class and is defined in RFC 9110.
Loading the workbench.
About HTTP 422
What Does HTTP 422 Unprocessable Content Mean?
The syntax is fine but the content fails validation. Common in JSON APIs. The code is registered with IANA and defined in RFC 9110.
Client error: the request has a problem, so it cannot be fulfilled as sent. Every code from 400 to 499 shares that general meaning, so a client that does not recognise 422 must treat it like 400.
When Do You See a 422 Response?
422 Unprocessable Content means the server understood the request and its syntax is valid, but the content cannot be processed as given. It is the usual answer for validation failures in JSON APIs: a required field is empty, a date is in the past, an email address is malformed, or a value is out of range. Frameworks such as Rails, Laravel, and FastAPI return it by default for validation errors.
How Do You Fix a 422?
Servers should return a body that lists each failing field and why, preferably in a consistent format such as application/problem+json with per-field errors. Clients should display those messages next to the relevant inputs, fix the data, and resend; retrying unchanged will fail again. Use 400 instead when the body cannot be parsed at all, such as invalid JSON.
What Does a 422 Response Look Like?
HTTP/1.1 422 Unprocessable Content
Content-Type: application/problem+json
Content-Length: 214422 is not cacheable by default: a browser or CDN stores it only when Cache-Control or Expires explicitly allows it.
To inspect a real one without sending it anywhere:
- Copy the response headers from your browser Network tab, or from
curl -i. - Paste them into the Header decoder to see every header explained.
- Check caching in the Cache lane.
Which Status Codes Are Related to 422?
- 400 Bad Request: The request is malformed: bad syntax, invalid framing, or an unreadable body.
- 409 Conflict: The request conflicts with the current state, such as an edit conflict or a duplicate.
- 415 Unsupported Media Type: The server does not accept this Content-Type or Content-Encoding.
Browse every code on the HTTP status codes page.
What Other Lanes Are in the Reference Section?
- HTTP status codes: Every IANA-registered status code, with a page per code.
- MIME types: File extensions to Content-Type, searchable both ways, plus a Content-Type parser.
- HTTP methods: GET, POST, PUT, PATCH, DELETE and the rest: safe, idempotent, cacheable.
Elsewhere in 2http: Header decoder, Cookie decoder, Cache-Control decoder, CORS checker, User-agent parser, and all eleven lanes on the 2http home page. Part of the 2suite.io privacy-first ecosystem.
Frequently Asked Questions
Should validation errors be 400 or 422?
Many APIs use 422 for well-formed but invalid data and 400 for unparseable requests. Both are acceptable if your API documents and applies the choice consistently.
Is HTTP 422 an error?
Yes. 422 is a client error response: the problem is in the request, so repeating it unchanged will usually fail again.
Is a 422 response cacheable by default?
No. Caches store a 422 only when Cache-Control or Expires explicitly allows it.
How Can You Verify That Nothing Leaves This Browser?
You do not have to take our word that your headers stay here. Developer tools show every request a page makes, so you can watch this page work and confirm that nothing is sent. The check takes under a minute.
- Open your browser developer tools with
F12, orCmd+Option+Ion a Mac, and select the Network tab. - Reload the page and let it finish. You will see the page's own files, its web fonts, and one anonymous page-view request. Nothing has been typed yet, so none of them can contain your headers.
- Click the clear icon in the Network tab so that the log is empty.
- Paste real headers into any lane and read the result.
- Look at the Network tab again. It is still empty. For extra proof, turn on offline mode after the page loads and every lane keeps working.
Only two things can add a line to that log, and neither carries your headers. Submitting the feedback form sends the vote and comment you typed. Typing characters in a script the page has not displayed yet, such as Cyrillic or Greek, can make the browser fetch the matching font file, and that request names only the font.
2http never sends a request on your behalf: the request builder writes code for you to run, and the meta inspector reads source you paste instead of fetching a URL. The production site also sends a Content-Security-Policy header that tells your browser to refuse connections to anywhere except this site and the anonymous analytics endpoint.