An Authentication Error Has Occurred
On Thursday, you may have noticed that your Fire TV/Stick wasn't displaying your apps properly.
Or, you tried to search for an application to install and it wasn't there.
You probably saw the message, "An authentication error has occurred."
This was a problem on Amazon's side and it has now been fixed.
But, for those of you still having this problem, there is a fix.
One of my devices kept displaying this error and I fixed it by going into Fire TV Settings / My Account and I de-registered my device and then re-registered it.