# Why did my API call return 400?

Because validation is strict on purpose. Rather than guess at what you meant, the API refuses the request with { "error": "bad_request" }.

The usual causes are an id that is not a well-formed uuid, a limit or offset outside its allowed range, an unknown value for an enumerated filter, a text value over its length cap, or a body that is not a valid JSON object.

Two behaviors save you most of the guesswork: an empty string is treated exactly like leaving the parameter off, and a query parameter the endpoint does not recognize is ignored rather than rejected. So fix the one argument that failed and retry once. Never retry the same call unchanged.

Read online: https://docs.closemagnet.com/articles/questions/why-did-my-api-call-return-400