> 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/data-api-sdk/api-endpoints-errors-and-migrations/request-body-strict-typing.md).

# Why does authenticateUser return a malformed request body error?

**A malformed request body error usually means a field is the wrong type**, for example `reference_id` must be a string, not an integer.

Newer Terra infrastructure enforces typing strictly per the API spec, so values that previously slipped through must now match the documented types.