Step to reproduce:
1. Any user with valid e-mail is created by admin (e.g. User1) ;
2. Any site is created by admin;
3. User1 is invited to the site with any role.
4. User1 is logged in Share.
5. User1 is navigated to My Task dashlet and click Invitation to join site link.
6. Click Accept or Reject button for invitation.
7. Open e-mail and click link below phrase "To accept this invitation click the link below" or "If you do not want to join the site then click here:"
The window with notificarion is appeared. No error is occured.
Error in log (see att.).