The query string "redirect_uri" is missing or invalid

 

Symptoms

When trying to access Appit from Site Contents, the following error occurs:

Sorry, something went wrong
The query string "redirect_uri" is missing or invalid.

 

Diagnoses

This is a known issue related to a change made to the new SharePoint UI.
 

Resolution

Reverting to the Classic SharePoint UI resolves the issue. There is an active investigation open into this issue.