Добавьте этот код AutomaticMigrationsEnabled = false;
к:
internal sealed class Configuration :
DbMigrationsConfiguration<ContosoUniversity.DAL.SchoolContext>
{
public Configuration()
{
AutomaticMigrationsEnabled = false;
}
protected override void Seed(ContosoUniversity.DAL.SchoolContext context)
{
// This method will be called after migrating to the latest version.
// You can use the DbSet<T>.AddOrUpdate() helper extension method
// to avoid creating duplicate seed data. E.g.
//
// context.People.AddOrUpdate(
// p => p.FullName,
// new Person { FullName = "Andrew Peters" },
// new Person { FullName = "Brice Lambson" },
// new Person { FullName = "Rowan Miller" }
// );
//
}
}