Unable to Verify App

Unable to Verify App when opening apps, all of them, doesn't matter who they are from.

Saw this question asked in the support pages a few times but every time someone claims that the user has side loaded / jail broken the device or that it is a problem with the app and to contact the app developer.

The problem also occurs with Messages, Phone, Mail, FaceTime, Weather, etc; these are all basic Apple apps loaded by default. It occurs with non-Apple applications as well. Usually there is the warning "Unable to Verify App", but sometimes it just locks up the device for a brief while and then the app is no longer active as it cannot be brought back up and must be restarted, only to fail again with the "Unable to Verify App" issue.

This is a non-jail broken iPad, recently upgraded to 16.3.1, 8th gen, MYLE2LL/A. The upgrade went poorly, when it rebooted after upgrading it went into a continuous reboot loop. This is the third upgrade this has occurred, thought not with each upgrade, around 3 of the last 7. Was forced to start over with a restore which lost all data. It's confusing on how to restore a backup and not upgrade, it does not seem possible which results in loosing all data after it is complete.