Updating EDMX gives build error

I have asp.net MVC application in which I am using database first approach , I have created Country , Cities and District table with following schema

Country(Id,Name)

City(Id,CountryID,Name)

District(Id,City_Id,Name)

Now I like to Add Country_ID as well into the district Table I am adding it in Database level and Updating my model from designer but after update when I tried to save I am getting lot of build errors 

"Severity    Code    Description    Project    File    Line    Suppression State
Error    CS1061    'Activity' does not contain a definition for 'User' and no accessible extension method 'User' accepting a first argument of type 'Activity' could be found (are you missing a using directive or an assembly reference?)    PPDMS    D:\PPDMS-Backup_Lahore\PPDMS_after_File_Upload_To_folder\PPDMS\PPDMS\Controllers\ActivitiesController.cs    110    Active"

like this how to fix it without doing this change i got no build error