XF 1.5 Cannot log back into the forums


New member
We're in process of moving XenForo to a new server/environment. The new server has the same code, same database as the current production server.

However, on the new server, when an existing user tries to log back in, following error is shown, and they can't log in anymore:
  • User names must be unique. The specified user name is already in use.
  • Email addresses must be unique. The specified email address is already in use.
What would cause this?