422 Unprocessable Content

I can read it. It just makes no sense.

What it properly means

The request was well formed but could not be followed because of semantic errors, such as failed validation.

Class
4xx Client error: you fucked up
Defined in
RFC 9110, section 15.5.21

Get one yourself

This endpoint really answers with 422. Point your client at it and see what it does.

curl -i https://httpcodes.dev/api/422

People mix this up with

  • 400 Bad Request422

    Can't read it, or read it and it's wrong?

    400 is for a request the server cannot even parse: broken JSON, bad framing. 422 is for one that parses fine but fails the rules, like a missing required field or an end date before the start date.