> For the complete documentation index, see [llms.txt](https://docs.tryterra.co/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tryterra.co/faq/help-topics/connecting/connection-errors-and-api-responses/reference-id-must-be-string-422.md).

# Why does the auth endpoint return 422 errors?

A `422` on the [authentication endpoint](https://docs.tryterra.co/health-and-fitness-api/user-authentication/authentication-flow) 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.