iCloud is stuck in a sign-in loop on my Mac so nothing syncs with it, including iTunes and Photos.

Hello One4Hope,

If I'm understanding you right, you're unable to sign into iCloud on your Mac, so you've been unable to sync successfully. I know how important it is to have iCloud working correctly on all of your devices. I'm happy to help you resolve this.

I recommend taking a look at this support article: Get help with iCloud. Those steps are designed to help with iCloud issues like the one you're experiencing. Make sure you try out the steps under the "Get started" section, as well as any other relevant sections listed below that. If you continue to experience the same thing, respond back with answers to the following questions:

• What exactly happens when you try to sign in? If you receive any errors, what do they say?
• Are you attempting to sign in via System Preferences > iCloud?
• Are you able to login successfully when you go to iCloud.com?

Thanks for using Apple Support Communities.

Take care.

Might be a corrupt .plist.

Do a backup, preferably 2 backups on 2 separate drives.

Quit System Preferences.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J.  When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder.  Select Library. Then go to Preferences/com.apple.systempreferences.plist.  Move the .plist to your desktop.

Restart the computer, open the application, and test. If it works okay, delete the plist from the desktop.

If the application is the same, return the .plist to where you got it from, overwriting the newer one.

Thanks to leonie for some information contained in this.

Nothing on this page seems to apply to my case. When I attempt to sign in to iCloud through System Preferences, I get a flag that says.

"XXXXX@me.com is already signed in to iCloud

To use this Apple ID as your primary iCloud account, delete it from Internet Accounts and sign in again."

There is a button which states "Open Internet Accounts...

When I click on this it takes me to the Internet Accounts page, but iCloud does not show up in the left column so I can't sign out.

I'm currently unable to access iCloud through the normal process. I can do it using Safari, but that is extremely limiting.

I think maybe contacting Apple Support is your best option for now: https://support.apple.com/contact Use the Apple ID link.

Are you having trouble using your Apple ID elsewhere. That's where the problem may lie, with your Apple ID. Try signing into your account at Apple.com.

No problem on 3 iPads, and another laptop. I deleted the two problem computers from my Apple.ca Account. When I try to sign in with my problem laptop it show the same behaviours as noted above.