Every time I try to sign in to iMessage on my computer with my Apple ID, I get "An unknown error occurred" and can't sign in

Hello joerichumich,

It seems that you're unable to sign in to iMessage on your Mac. We'd love to provide you with a few steps that may help resolve the issue:

1. 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.

2. Check for a service outage

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

3. 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.)

4. 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. 

5. 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.

6. Reset NVRAM

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

7. 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.

Click here for more details: If you can't sign in to your iMessage account or FaceTime on your Mac

Hope this helps.

Take care.