I have a lot of SharePoint site-collections (SharePoint 2016 on-premises) where I installed my add-in. All is working correctly but there is a problem in a single site-collection.
In the problematic site the users get always error 500 when they call
The problem is present only with normal users (readers or collaborators), the administrators can call the API without any problem. All the site-collection are provided with the same PowerShell routine.
I can't find the details of the error in the event viewer.