All Commands / Tile Taps suddenly result in "Error" or "Not Authorized"

The toast message may say "Error:" or "This request is not authorized by the specified Access Token".

Unless this is a temporary system-wide or SmartThings Platform issue, the following may help:

This error may be resolved by just "re-authorizing" your Location(s):

1. Go to My Locations page in ActionTiles and tap the (+) button.
   
2. Go through the SmartThings Authorization process again. It should not hurt anything and likely will reset the SmartThings Access Token.