ICLOUD_UNSUPPORTED_DEVICE on macbook air.

Hi. I had this problem on a macbook air 2020 M1 with Monterey installed (fresh install). I first tried a restart but this didn't fix the problem. I eventually resolved it by signing into the app store, and then signing into iCloud via system preferences.

Thanks for reaching out, Mak1111.

If you haven't done so already, restart your MacBook Air: Shut down or restart your Mac Sometimes a restart can help resolve issues.

Have you tried the steps in this article for issues when trying to sign in with iMessage on the MacBook Air? If you can't sign in to your iMessage account or FaceTime on your Mac - Apple Support

Check your Internet connection

Make sure that your Mac is connected to the Internet. You should be able to load web pages or receive email, for example.

Check for a service outage

Check the Apple System Status page for a temporary outage affecting iMessage or FaceTime.

Check your Date & Time settings

Choose Apple menu () > System Preferences, then click Date & Time. Make sure that the date, time, and time zone are correct.

If the ”Set date and time automatically” checkbox is selected, deselect it and select it again. (If the checkbox is dimmed, click  and enter your administrator password.)

Make sure that your software is up to date

Learn how to update your Mac software. Software updates can improve the stability, compatibility, and security of your Mac, and might also resolve the issue. 

Check your Apple ID

To make sure that your Apple ID and password are correct, go to the Apple ID account page and sign in with the same Apple ID that you're using with Messages and FaceTime. If that works, open the app and take these steps:

Messages: Choose Messages > Preferences, then click Accounts. Select your iMessage account, then click Sign Out. Now sign in again with the same Apple ID you used on the Apple ID account page.

FaceTime: Choose FaceTime > Preferences. In the Settings tab, click Sign Out. Then sign in again with the same Apple ID you used on the Apple ID account page.

Reset NVRAM

In case the issue is related to any of the settings stored in NVRAM, reset NVRAM on your Mac.

Check for third-party software

If you installed firewall, security, VPN, or other third-party networking software, make sure that the software isn't blocking any of the network ports used by iMessage and FaceTime. If necessary, disable the software and then try using your iMessage account or FaceTime again.

See if the same thing occurs in safe mode: How to use safe mode on your Mac - Apple Support

Safe mode prevents your Mac from loading certain software as it starts up, including login items, system extensions not required by macOS, and fonts not installed by macOS. It also does a basic check of your startup disk, similar to using First Aid in Disk Utility. And it deletes some system caches, including font caches and the kernel cache, which are automatically created again as needed.

Keep us posted.

Cheers!

Strange! Can’t tell you what the solution is (maybe someone with a bit more expertise can answer) but what I would try: reset NVRAM (if intel Macbook) and otherwise try a clean reinstall of OS. You could also try to sign in on safe mode but I haven’t really found that to be all that useful with the issues that I have had previously

I have this problem on my 2021 MacBook Air. It's up to date, I've restarted, shut down, and done everything above that I can, but it still won't sign into my iCloud. I know my iCloud works because I've signed in recently on other devices. The App Store, Messages, and FaceTime won't work when try to I sign in either. Please help.