SharePoint Dragons

We experienced two issues when adding SharePoint add-ins and thought to share.

Issue: Add-ins can be added to some sites but not to others

Cause: Certain add-in permissions require the activation of specific SharePoint features. For example, if your add-in requires the News Feed (Social) feature, the activation of the Sitefeed web scoped feature is required. If this is not the case, the add-in just won’t appear via Site Contents or via Site Contents > add an app. SharePoint won’t give you a hint via the UI that this is happening.

Issue: The adding of an add-in repeatedly fails

Diagnostic info: Checking the ULS log files indicates that adding the add-in results in a Critical error that states the following:

“Insufficient SQL database permissions for user ‘Name: NT AUTHORITY\IUSR SID: [some SID] ImpersonationLevel: Impersonation’ in database ‘SP_UsageAndHealth’ on SQL Server instance ‘[Some SQL instance name]’. Additional error information from SQL Server is included below.  The EXECUTE permission was denied on the object ‘prc_CountAppInstanceData’, database ‘SP_UsageAndHealth’, schema ‘dbo’.”

Cause: The error message isn’t helpful because it turns out it doesn’t provide a clue towards the real solution. In our case the problem was caused because the site quota limits had been reached that are associated to the site collection where we want to add the add-in. After fixing that, the add-in could be added successfully.