After adding new gmail account, receiving message "unknown command 5mb150836800qkd"

I just created a new Gmail account, and after upgrading Thunderbird was finally able to add the account successfully. Unfortunately, now I am receiving the message: The current operation on 'Inbox' did not succeed The mail server for account .... responded: Unknown command 5mb150836800qkd" Ummm, is there some other command that might be used? thanks much, AudreyV