The model backing the 'DataContext' context has changed since the database was created

I am not sure if you found the answer to your problem, but this other answer I found here actually did it for me: Entity Framework model change error

I actually ended up deleting the __MigrationHistory table in SQL Server which I didn't know it was being created automatically.

The article also talks about the option to not generate it I think by using this instruction: Database.SetInitializer<MyDbContext>(null); but I have not used it, so I am not sure if it works like that

This worked for me.

Go to Package Manager Console and Run - Update-Database -force