The address book is already connected to another Contacts+ account. Please contact support for assistance.
This notification usually means that the account you're trying to connect is already associated with another Contacts+ account. Since one contact source can only be associated with one Contacts+ account, you aren't able to connect it twice.
If you have created multiple accounts accidentally, we simply suggest deleting one of them. After that, you should be able to connect the address book which returned this error without any issues.
To delete the accidentally created Contacts+ account, go here -> Close Account.
You've reached the contact limit for your account.
To explain a bit, Contacts+ has a strict storage limit of 25,000 contacts per account. This is implemented due to the storage limit for personal accounts in Google. We've adopted that limit since it significantly simplifies our syncing system for the challenge of syncing across Google, iCloud and Exchange accounts.
When you have exceeded your limit of contacts, you will get a notification in your Contacts+ address book letting you know. A few features will also be disabled when going over your limit - when over your limit you will not be able to add additional contacts or sources.
To remove this limitation, I'd suggest deleting specific contacts (feel free to use our smart tags to filter out contacts without email addresses / phone numbers) or disconnect contact sources (Twitter, Foursquare).
Account can't be deleted. A paid API account is associated with your apps account. Contact Support to resolve this issue.
This means you also have an API account with us which is why you can't delete your apps account. If you're not planning to use your developer account in dashboard.fullcontact.com. Unfortunately, since these two accounts are linked together, you cannot delete one without deleting the other.