Unknown error message

Hello Gemst0ne,

Thank you for reaching out to Apple Support Communities, and we'll be happy to help in any way we can. We understand you're having issues with signing into your Apple ID on your Mac. Try the steps here to see if they resolve the issue: If you can't connect or sign in to iCloud - Apple Support

"If you've set up your Apple ID and need help signing in to or using iCloud, follow these steps.

Get help signing into iCloud

Before you begin, check the Apple System Status page to make sure there are no outages or scheduled maintenances currently affecting iCloud and make sure that you’re signed in to iCloud with the same Apple ID on all of your devices. 

If you can't remember your Apple ID or password

If you can't remember your Apple ID, check these settings and services to find it. If you've forgotten your Apple ID password, learn how to reset it. 

If you get a message that your Apple ID is locked or disabled

If you or someone else enters your password, security questions, or other account information incorrectly too many times, your Apple ID automatically locks to protect your security and you can't sign in to any Apple services. Learn how to unlock your Apple ID. 

If you can't sign in to iCloud.com

Learn what to do if you have trouble signing in to iCloud.com. 

If you're not able to sign in using cellular data only

Make sure that your iPhone, iPad, or PC has a strong Internet connection and that you've turned on cellular data on your iPhone or iPad by going to Settings > Cellular or Mobile Data. If this setting is off, you might not be able to access your Apple ID and iCloud when not connected to a Wi-Fi network. 

If you're having trouble receiving verification codes, or your verification code is rejected

Learn how to get a verification code and sign in to iCloud with two-factor authentication. If your device is running iOS 8 or OS X Yosemite or earlier, sign in using two-step verification instead.

If you see a Could Not Create Apple ID or Could Not Set Up iCloud message

If you see one of these messages, it means that you have exceeded the number of new Apple IDs you can set up with iCloud on a single device in one year. Learn what to do. 

Other password prompts you might see

If you are repeatedly prompted to enter your Apple ID password on your Mac or iOS device

• If you have recently restored your iPhone, iPad or iPod touch from an iCloud backup, the restore may not have completed. Stay connected to a reliable Wi-Fi network and power source until the restore finishes. Follow these steps if iCloud Backup couldn't be completed or you can't restore. 
• If you recently changed your Apple ID password, you might need to update your sign-in informationwith iCloud services you use. Make sure that each service is using your updated sign-in information on your device.
• Check if you have Automatic Downloads enabled. If there is content ready to be downloaded, you may be prompted to enter your Apple ID and password to continue. Learn how to resume interrupted downloads. 
• If you are an organizer, parent, or guardian of a Family Sharing group, check if the prompt is a request from a child family member to make an iTunes Store purchase. You can then approve or decline the request. 

If you want to sign in to a third-party app but your password is rejected

If you want to access your iCloud information from a third-party app, you need to use an app-specific password. This helps protect your account by allowing you to sign in securely. Learn how to create and use app-specific passwords. 

If you still need help

If you still need help signing in to iCloud, update your iPhone, iPad, and iPod touch to the latest version of iOS or iPadOS, and your Mac to the latest version of macOS. See the iCloud system requirements for more information."

We hope this helps.

Cheers!