Entity Framework 4.3.1 add-migration error: "model backing the context has changed" - entity-framework-4.3

Question

I'm getting an error when trying to run the EF 4.3.1 add-migrations command:
"The model backing the ... context has changed since the database was created".
Here's one sequence that gets the error (although I've tried probably a dozen variants which also all fail)...
1) Start with a database that was created by EF Code First (ie, already contains a _MigrationHistory table with only the InitialCreate row).
2) The app's code data model and database are in-sync at this point (the database was created by CF when the app was started).
3) Because I have four DBContexts in my "Services" project, I didn't run 'enable-migrations' command (it doesn't handle multipe contexts). Instead, I manually created the Migrations folder in the Services project and the Configuration.cs file (included at end of this post). [I think I read this in a post somewhere]
4) With the database not yet changed, and the app stopped, I use the VS EDM editor to make a trivial change to my data model (add one property to an existing entity), and have it generate the new classes (but not modify the database, obviously). I then rebuild the solution and all looks OK (but don't delete the database or restart the app, of course).
5) I run the following PMC command (where "App" is the name of one of the classes in Configuration.cs):
PM> add-migration App_AddTrivial -conf App -project Services -startup Services -verbose
... which fails with the "The model ... has changed. Consider using Code First Migrations..." error.
What am I doing wrong? And does anyone else see the irony in the tool telling me to use what I'm already trying to use ;-)
What are the correct steps for setting-up a solution starting with a database that was created by EF CF? I've seen posts saying to run an initial migration with -ignorechanges, but I've tried that and it doesn't help. Actually, I've spent all DAY testing various permutations, and nothing works!
I must be doing something really stupid, but I don't know what!
Thanks,
DadCat
Configuration.cs:
namespace mynamespace
{
internal sealed class App : DbMigrationsConfiguration
{
public App()
{
AutomaticMigrationsEnabled = false;
MigrationsNamespace = "Services.App.Repository.Migrations";
}
protected override void Seed(.Services.App.Repository.ModelContainer context)
{
}
}
internal sealed class Catalog : DbMigrationsConfiguration<Services.Catalog.Repository.ModelContainer>
{
public Catalog()
{
AutomaticMigrationsEnabled = false;
MigrationsNamespace = "Services.Catalog.Repository.Migrations";
}
protected override void Seed(Services.Catalog.Repository.ModelContainer context)
{
}
}
internal sealed class Portfolio : DbMigrationsConfiguration<Services.PortfolioManagement.Repository.ModelContainer>
{
public Portfolio()
{
AutomaticMigrationsEnabled = false;
MigrationsNamespace = "Services.PortfolioManagement.Repository.Migrations";
}
protected override void Seed(Services.PortfolioManagement.Repository.ModelContainer context)
{
}
}
internal sealed class Scheduler : DbMigrationsConfiguration<.Services.Scheduler.Repository.ModelContainer>
{
public Scheduler()
{
AutomaticMigrationsEnabled = false;
MigrationsNamespace = "Services.Scheduler.Repository.Migrations";
}
protected override void Seed(Services.Scheduler.Repository.ModelContainer context)
{
}
}
}

Answer 1

When using EF Migrations you should have one data context per database. I know that it can grow really large, but by trying to split it you will run into several problems. One is the migration issue that you are experiencing. Later on you will probably be facing problems when trying to make queries joining tables from the different contexts. Don't go that way, it's against how EF is designed.