How do I clear this error?

[Google Contacts]Uploading item(s) to folder ‘jimnc9@gmail.com/Contacts’ failed due to the following error: Can not remove all contact group memberships. Contact must always be in at least one contact group.

Best solution is to remove the Gmail account from eM Client, then add it back again.

Uninstalled ENC, rebooted, reinstalled, same error.
Should I have deleted the database?

No, remove the account from eM Client. NO need to remove eM Client.

To do that go to Menu > Accounts and click on the Gmail account.

Then click on the Delete icon.

That didn’t work either

In eM Client, go to Menu > Accounts.

Click on the Gmail account, then click on the Delete icon. This will remove the Gmail account from eM Client.

Next, click on the Add Account icon and add the account again using the Automatic Setup.

Once that is done, click on Save & Close.

The error will no longer be there.

Before I do that, will this lose any emails I’ve downloaded from my Gmail account into eM Client? Will I have to restore my settings or rules?

Nothing is at risk. Just exit and reload.