Contacts can't connect to the account

This works: Go to your "system preferences" in launchpad and then go to "mail, contacts and calendars" check mark everything for each of your accounts which is allowed. I no longer have that pop-up asking for a password! Still, not everything should be checked, because it doubles up on some contacts. .... more to come ...

... and then delete duplicates. I cannot edit my post!

My account is already set up correctly but I, too, still keep getting that message and cannot sync my iMac with my yahoo contacts

Apple support article:

Contacts/Calendar – Troubleshooting Sync

I too have this problem. I thought it was something to do with my BT password, which I changed, but to no avail.

My autofill is not working either and I think it's connected to the above fault. I can get round this problem but it really annoys me when things don't work right!