Can't log in into iCloud after installing macOS Mojave on MacBook Pro 2013 Retina I updated my MacBook Pro to macOS Mojave. Everything was working fine except iCloud, it was not synchronizing data. 

So I thought I sign out and back in. 

But if I try to sign in, the wheel spins, and after a while it goes back to the original screen where you have to enter your Apple ID without error message.

After trying a restart, deleting cache etc. I created a new user, here everything is working.

But I want it working with my original account with all my data.

There seems to be a problem with some keychain file:
Since you have confirmed that a new user can sign in, your next step is unfortunately to engage Apple technical support. 

You’ve ruled out date and time errors, an error on the network and an error on the cloud side of your account that’s like a lockdown or other massive error. You should expect to be requested to make a support pin to indicate that you allow Apple engineers to support you with your personal data.