unknown error occurring with iMessage on Mac

I went to Setting > Apple ID > Overview, in the bottom left I clicked signed out. After that is done, I then opened up messages and it stopped giving me the sign in screen, I then processed to sign back in via Settings. All good now. Hope it helps someone.

i found a fix for it. I tried LITERALLY EVERYTHING and it wouldnt work. I was getting the "an unknown error has occured" only on iMessage even though i was signed into iCloud.

1.) sign out of your user account

2.) create a brand new user (as if your wife or child etc was creating a seperate profile on the computer)

3.) sign in with iCloud, and with iMessage in the new profile and it should work

4.) next, sign out of that new profile you created

5.) go back and sign into your original profile on the computer and try signing in.

And iMessage works for me now on the original computer profile (user)

That was what worked for me. An apple rep suggested that to me after i tried 4000 other things to try and fix it.

Update: I fixed it!

My old computer was experiencing a different iCloud problem: after signing out, I was unable to sign back in, and kept getting an error saying I was already signed in. This was the same account that I had migrated to my new computer that was experiencing the "unknown error" in Messages. I found this thread on StackExchange:

https://apple.stackexchange.com/questions/340155/account-is-already-signed-in-to-icloud-in-mojave-but-its-not?newreg=804cdc6d23fb475dbbf208c736a5e109

And followed the suggestions to clean my System Caches with Onyx and then run the following Terminal command:

defaults delete MobileMeAccounts

Running the Terminal command immediately allowed me to sign into iCloud on the old Mac. I then erased my new Mac, re-installed Monterey, re-migrated my user account and all my data, and everything worked. No more "unknown error." I also uninstalled Sophos FWIW, although I'm not sure that was related. Just something that was suggested to get rid of some pesky Console timestamp error messages.

Thanks for the info; that's really frustrating (and I know because I spent 10 days trying to fix this problem myself before I finally cracked it). I tried a bunch of the steps you posted above to no avail.

First I would run a backup of the new computer. Then I would try signing out of iCloud on the new Mac, opening Terminal and running the following command:

defaults delete MobileMeAccounts

I got that command from here:

https://apple.stackexchange.com/questions/340155/account-is-already-signed-in-to-icloud-in-mojave-but-its-not?newreg=804cdc6d23fb475dbbf208c736a5e109

That's the step that fixed everything for me. Although, in my case, my old Mac was also having problems with iCloud that started after I tried signing out of iCloud everywhere to fix the Messages problems on the new Mac.

So I ran the Terminal command on the old Mac which fixed the iCloud problems on that computer, erased the new Mac and reintalled MacOS, used Migration Assistant to copy all my data to the new Mac, and after that Messages worked on the new Mac. So your case might be a little different. I also used Onyx by Titanium Software on the old Mac to just clear out the System Cache and run some routine maintenance before running Migration Assistant.

How long have you been using the new Mac? How feasible would it be to do a erase and reinstall? I know it would suck to do that if you've already tried similar steps, but it might be necessary—I went through 5 erase-and-reinstalls before I finally fixed everything.

For anyone else who comes across this later, I experienced this problem this morning. Very strange in that it just came out of the blue after no issues for so long. I tried a lot of things as well but ended up just signing out of iCloud entirely, rebooting and then signed back into iCloud (by this, I mean machine-wide in the Internet Accounts section of settings...doing this in Messenger alone got me nowhere). It fixed the problem.

Here's an update: Downgraded to BigSur and briefly saw I was logged into Messages (about 10 sec) then logged me out.

Created a new Apple ID, same thing.

Contacted previous owner, they'd had the logic board replaced. Turns out the serial number reported in "about this Mac" and the serial number on the iMac foot are different. going to contact them and see who did the replacement and see about settling the serial number issue, from what I've read today on the net, that difference can be my issue.

I'll post back next week with findings. Thank you again Jacob.

This error still happens with Monterey 12.1.

All I did was log out of the Apple ID in System Preferences and restarted my mac. That fixed the error.

Cheers!

Hello, and welcome to Apple Support Communities wbake,

We can see you've been using If you can’t turn on or sign in to iMessage or FaceTime, and are receiving an error message after upgrading to macOS Monterey.

Let's see if the steps included in this guide help: If you can’t send or receive messages on your Mac. Go through the first section and see if you're able to send iMessages. If not, under the "Learn more" section, there is a link to contact Apple Support. We'd suggest using this so they can work with you to resolve this with you.

Take care.

I was about to try jordanwinston's solution, but i just logged out of my user & then logged back in & then I was able to login to iMessage without getting the error.

Hi @Cnaz

I hope I am able to help. Looks like you're taking the right steps, except––after you create the new account, (don't create a temp account) you will go into the new account you've just created, sign in to your iMessage, and iCloud just like you did, like you mentioned it work after you're logged in, do not log out of the iMessage. Now switch over to the account that you're actually using that is giving you the unknown error, try signing in to the iMessage and iCloud –– this is when it worked for me. The only thing is that I have not deleted the new account I created because I'm afraid it will stop working on the account I am using. Let me know if it works!

Eesh. I know the feeling, though. Maybe I was the fortunate one. I wish had another solution, but a simple restart solved my issue. Best of luck, John!

Jordan's fix of creating a new profile worked for me. I still got the iMessage error on the new profile but once I signed out of it and back into my original profile, iMessage worked again.

Hello! I got an MBP with BigSur 11.6.2.

I had this issue today for the first time ever.

i restarted the Mac and everything turned on again. conversations are not synced but it's okay

haha thanks! Happy to help! it was driving me INSANE so i figured it would help others if i posted the solution to it. Typing from iMessage on the computer is key to productivity for me so not being able to was really annoying.

Happy to help! Thanks!

Okay…I have spent hours and hours trying to find a solution to this. It’s literally been months since I’ve been able to login to my messages and FaceTime. I was using my phone for FaceTiming and it was a pain and I was ready to get rid of my Mac since I couldn’t do a lot of the things I bought it for. Your solution is literally the diamond in the rough. If I could pay you I would haha. Thank you!!!