This is the error message (Oops! and all) served by Nest when the login attempt is made for some of my users. It is in fact right now blocking my app from being reviewed by Apple, because they’ve run into this same error message, using the same login credentials that for me work perfectly.
I really can’t explain it, but I can see that the message is coming from the Nest login page sequence, before my app is even really doing anything. The problem is occurring within the Mac app, that is presenting the login page in the webview, only seems to happen in rare instances, and doesn’t seem to be tied to a specific user account.
I believe this problem has started happening after the Nest login page redesign - previously it had a multi step procedure for switching from one user to another, now it just requires pressing the “Not you?” link - so I can see that something has been changed recently