How to fix iMessage and FaceTime activation issues on macOSGetting an authentication error trying to log into iMessage or FaceTime? Try this fix!
Apple rightfully has a reputation of having its products "just work". And 99% of the time that adage holds true. Until it doesn't. When things do go wrong, Apple's error messages are cryptic, at times offering no obvious clue as to how to remedy them. One such error is the "Authentication Error" message when trying to log into iMessage and FaceTime on your Mac, even if you've successfully logged into iCloud.
The problem
The potential fix
Final comments
The problem
For a non-obvious reason, my previously properly running Mac could no longer log into iMessage or FaceTime in spite of being successfully logged into iCloud. Notes synced, Documents synced, Photo stream working, continuity functional, etc.
Trying to log into iMessage triggers my two-factor authentication mechanism as expected. But when prompted for my iCloud username and password, and after a long timeout period, I simply get an "Auth...
Source:
How to fix iMessage and FaceTime activation issues on macOS
