API returns 400: Unknown Error Occurred

I have 2 sites in which I am trying to load a collection from the REST API. One site is a “CMS site” and one is a “Starter site”. Loading a collection via GET /collections/{collection_id} works for the CMS site. For the starter site, I get a 400 error: Unknown Error Occurred

The collection I’m trying to load has 1 published item. The collection ID is correct, otherwise the error would be: 400 ValidationError: Provided ID is invalid

I can’t tell why it’s not working for the Starter site. Appreciate any help!

Clarifying that this is the v1 API, not the new beta API.

Hey @MattDL, welcome to the forum!

To confirm are you using a legacy API token for your Starter site? This error often occurs when hitting a v1 endpoint but using a v2 API token.