If you have received error 641, this is due to another manger accepting the invitation to join the same team you were invited to join. It is possible for the commissioner to send multiple invites to join the same team. Once a manager has accepted an invitation, it will invalidate any additional invitations for that particular team.

In order to join the league you were invited to, you will need the commissioner to send you a general invite or an invite from another team that has not yet been taken over or  provide you with the league ID # and password.

Also, please note that if you have already accepted a league invite that was sent to you via email, and are trying to access your league via the invite link, you will also get error 641. Instead, you'll need to access your team by logging into your league with your personal log in credentials.