After updating to b2, I changed my Apple ID password. I've been able to sign back into iMessage on iOS 8 stable, and a different Mac running b1. However, on this Mac running b2, I get an alert "Verification Failed An unknown error occurred.", then the iMessage sign in window displays a message "Could not sign in to iMessage An error occurred during activation. Try again."
I've been trying off and on for the past day and a half without any luck.
Quite a few people have managed to resolve out-of-whack iCloud issues by locally deleting the iCloud account files, rebooting, and trying again:
i.e. delete the files in the following folder
/Users/<YOUR HOME FOLDER>/Library/Application Support/iCloud/Accounts
Then reboot.
And if that doesn't work, you can try moving one or more of the:
/Users/<YOURUSERNAME>/Library/Containers/com.apple.soagent/Data/Library/Preferences/com.apple.messageshelper.*.plist
files to the desktop (depending on what you think is most relavent to your issue). A reboot may be necessary to for the .plist to be recreated and fix to take effect.
This Mac has never been signed into iCloud, so that folder doesn't exist. I nuked the entire com.apple.soagent folder, emptied the trash, rebooted, and still unable to login, same error.
(I was able to use the "delete iCloud/Accounts" technique on a different Mac to fix a b2 install issue.)
Have you tried moving the iMessage account .plist to the desktop and rebooting?:
/Users/<USER FOLDER>/Library/Preferences/com.apple.imservice.ids.iMessage.plist
If it is a corrupted .plist then the above is the most likely, but there are a couple of other contenders too (if you have the enthusiasm for it):
/Users/<USER FOLDER>/Library/Preferences/com.apple.imessage.bag.plist
or any starting with com.apple.imservice.ids.iMessage. ... in the following folder:
/Users/<USER FOLDER>/Library/Preferences/ByHost/
Removed all but still not working. Also get "This Mac can't connect to iCloud" message everytime after rebooting.
I have this problem now, even though it is a 6 year old post. Fortunately, the solution still works, so thank you @Max108 !
/Users//Library/Application Support/iCloud/Accounts
Then reboot.
This worked for me.
