If you are trying to join a village using an invitation code and see an error message, there's a few reasons why that code wouldn't work:
- The code has already been used to join a village
- The code entered doesn't match the code sent to you in your email
- The invitation was canceled by the person that sent the invitation or another administrator within the village.
The best way to fix this is to contact the person who sent the invitation directly and ask them to re-send the invitation.