Entity Framework model change error
If you already deployed your application or you don't want remove data from database you must read about Code First Migrations. Here you have a link: http://msdn.microsoft.com/en-us/library/hh770484(v=vs.103).aspx
If you can delete database just do it. EF will create new database that match your model.
You can also disable creating/updating database structure by invoking the following code:
Database.SetInitializer<MyDbContext>(null);
If you delete the __MigrationHistory
table in SQL Server it should fix it.
I used database first to create a project after I had changed my database context and solved my problem:
Database.SetInitializer<Models.YourDbContext>(null);
Don't forget to handle the DbUpdateException