How to fix iMessage and FaceTime activation issues on Mac

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How to set up iMessage on your Mac
How to set up iMessage on your Mac (Image credit: Joseph Keller / iMore)
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Apple rightfully has a reputation for having its products "just work." And 99% of the time, that adage holds. Until it doesn't. When things do go wrong, Apple's error messages can be 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.

We know just how frustrating it can be when your best Mac isn't letting you use basic functions of the computer; the good news is there a fix for Message and FaceTime activation issues on macOS Big Sur.

The problem

For a non-obvious reason, my previously properly running Mac could no longer log into iMessage or FaceTime despite successfully logging into iCloud. Notes synced, Documents synced, Photos were working, 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 get an "Authentication Error."

The potential fix

The fix involves getting Apple's servers to re-initialize your Mac hardware to be allowed to access your iCloud services.

Log out of iCloud on your Mac

  1. Open System Preferences.
  2. Click Apple ID.

Log out of iCloud on Mac, showing how to open System Preferences, then click Apple ID (Image credit: iMore)
  1. Click Overview.
  2. Click Sign Out…

Log out of iCloud on Mac, showing how to click Overview, then click Sign Out... (Image credit: iMore)
  1. Follow the instructions to keep or delete iCloud data like calendars, reminders, and photos from your Mac.

Log out of iCloud on Mac, showing how click Keep a Copy (Image credit: iMore)
  1. Restart your Mac.

Log into your iCloud.com web account

  1. Navigate to iCloud.com in Safari.
  2. Log in with your iCloud credentials.

Log into iCloud.com, showing how to navigate to iCloud.com, then log in with iCloud credentials (Image credit: iMore)
  1. Click Account Settings.
  2. Click your problematic Mac under My Devices.

Log into iCloud.com, showing how to click Account Settings, then click on your Mac that's having issues (Image credit: iMore)
  1. Click the X next to the Mac.
  2. Click Remove.

Log into iCloud.com, showing how to click the X next to the Mac you want to remove, then click Remove (Image credit: iMore)
  1. Click Done.

Log into iCloud.com, showing how to click Done (Image credit: iMore)

Sign back into iCloud on your Mac

  1. Open System Preferences.
  2. Click Sign In.

Sign in to iCloud on Mac, showing how to open System Preference, then click Sign In (Image credit: iMore)
  1. Sign in with your iCloud credentials.
  2. Enter your Mac sign-in credentials.

Sign in to iCloud on Mac, showing how to sign in with your iCloud credentials (Image credit: iMore)
  1. Click OK.

Sign in to iCloud on Mac, showing how to click OK (Image credit: iMore)

Once you're signed back into iCloud on your Mac, you should automatically be signed back into Messages and FaceTime.

Final comments

This is but one solution (of the myriad of suggestions found online) that worked for me. Let us know in the comments if this fix helped you too!

macOS Big Sur

○ macOS Big Sur Review
○ macOS Big Sur FAQ
○ Updating macOS: The ultimate guide
○ macOS Big Sur Help Forum

Joseph Keller
Joseph Keller

Joseph Keller is the former Editor in Chief of iMore. An Apple user for almost 20 years, he spends his time learning the ins and outs of iOS and macOS, always finding ways of getting the most out of his iPhone, iPad, Apple Watch, and Mac.