Why does the auth endpoint return 422 errors?

A 422 on the authentication endpoint is most commonly caused by sending reference_id as an integer.

A 422 on the authentication endpoint is most commonly caused by sending reference_id as an integer. It is documented as a string and must be sent as a string.

Convert the value to a string and the error resolves.

Intermittent occurrences across different providers trace back to the same payload-type issue, not a provider outage.