Failed to merge new Sql connection string with the existing one because of DataSource mismatch. New DataSource = '{0}', existing ...

Failed to merge new Sql connection string with the existing one because of DataSource mismatch. New DataSource = '{0}', existing DataSource = '{1}'. If your Server or DataSource property is changed in the new connection string, make sure you set the password instead of trying to re-use the existing stored password.