You must sign in with your Apple Account (formerly Apple ID) to use iMessage on your Mac or sync your iPhone texts to it. It’s a simple process, but in some cases, you may see random errors that prevent you from logging in. Go through these quick tips if you see “An unknown error occurred,” “Error with Authentication,” or another similar message when signing into the macOS Messages app with your Apple Account.
Make sure you’re entering the correct details
If you type your Apple Account email address and password incorrectly, the app should display the appropriate message. But in some cases, it will simply throw the generic “An unknown error occurred” text in red color on the screen. Therefore, double-check that you’re entering the correct details. In case you have forgotten your Apple Account password, reset it quickly from iOS Settings or macOS System Settings.
Retry after force-quitting the app or restarting your Mac
It can also happen that even though you’re doing everything right, the app keeps showing an error message because it’s still hooked to the previous issue. To fix this, force-quit the Messages app by clicking the Apple icon in the top-left corner and selecting Force Quit. Then, reopen the app and try signing in again.
In case force-quitting it for the first time didn’t help, force-quit it again, and restart your Mac. Then, open Messages and try signing in. It should go through successfully.
Check Apple’s system status and try again after a while
Visit Apple’s system status page and make sure things like Apple Account, iCloud Account & Sign In, and iMessage are available. If there is an outage, wait and retry after a while.
Update to the latest version of macOS
If your Mac is on an older version of macOS or running macOS beta, update to the most recent build available for your computer.
Delete system files related to Messages
In case you still see the “An unknown error occurred” or some other similar message, follow these steps to delete the related system files and start fresh. Since you’re already signed out, deleting these should not cause any concern. After you restart, macOS will recreate these necessary files.
- Go to your Mac’s hidden Library folder by opening Finder, holding the Option key, and clicking Go > Library from the top menu bar.
- Find and open the Messages folder. Then, select all files and folders here and move them to the Trash. You can also move them to some other folder for safekeeping.
- Important: Restart your Mac.
- Open the Messages app and retry signing in. It should work.
Sign out of your Apple Account and sign back in
In case you continue facing the sign-in problem even after following the above tips, consider signing out of your Apple Account in System Settings. Then, restart your Mac and attempt signing in to Messages again.
If everything fails…
Lastly, if nothing works for you, I recommend waiting a few hours or maybe a day and then retrying. If you have already done that and the problem exists, try these as a last resort. I have listed the easiest ones at the top.
- Add a new user account to your Mac, set it up, and try signing in to your Apple Account in the Messages app there.
- Add another version of macOS to your computer (leaving your current setup untouched) and try signing into Messages there.
If you’re successful, that means there is an issue with your particular user account or macOS installation. Retry all the above solutions again, especially the one where we talk about deleting all the Messages files and starting over.
In case the problem continues, consider these two options:
- Reinstall macOS without deleting your existing data.
- Factory reset your Mac and set it up again.
One or a combination of the tips above should have solved the iMessage sign-in issue on your Mac. Let us know which one worked for you.
Also, check out: How to sync all your iPhone messages to Mac