The default DbConfiguration instance was used before the 'EntityFrameworkConfiguration' type was discovered

Question

 public class EntityFrameworkConfiguration : DbConfiguration
    {
        public EntityFrameworkConfiguration()
        {
            this.SetModelCacheKey(ctx =>         


        

Answer 1

In my case i have two different edmx files and both are in different class libraries. I got this error when i added those two libraries in the same project.

I don't have any single clue how is that sorted out but; when i call any method from my first DbContext class, the second one worked like miracle happened. It was throwing this error when second context class called first. My Ef version is: 6.4

Answer 2

If you are using Code-based configuration, try updating the config file thusly:

<entityFramework codeConfigurationType="MyNamespace.MyDbConfiguration, MyAssembly">
    ...Your EF config...
</entityFramework>

Answer 3

Your question doesn't state how you are using this custom DbConfiguration.

You could get this error a couple of different ways.

Configuration style setup

as described here: Entity Framework Config File Settings

Configuration as code

as described here: Entity Framework Code-Based Configuration (EF6 onwards) You can hack at this style by doing things like DbConfiguration.SetConfiguration(xxxx). I didnt find this useful at all.

What this really comes down to is how you construct your DbContext.

Configuration file style constructors https://github.com/aspnet/EntityFramework6/blob/master/src/EntityFramework/DbContext.cs#L75 With no arguments - EF6 is uses the configuraiton files to determine the right DbCofniguration to use

with some "connection string-like" arguments again EF6 is using configuration files to determine the DbConfiguration

no config, or bad config - and you will get this sort or exception

Configuration as Code style constructors https://github.com/aspnet/EntityFramework6/blob/master/src/EntityFramework/DbContext.cs#L139

I think this yields better control.

Attribute your DbContext, then use a manually created DbConnection

public class EntityFrameworkConfiguration : DbConfiguration
{
    public EntityFrameworkConfiguration()
    {
        this.SetModelCacheKey(ctx => new EntityModelCacheKey((ctx.GetType().FullName + ctx.Database.Connection.ConnectionString).GetHashCode()));
    }
}

[DbConfigurationType(typeof(EntityFrameworkConfiguration))]
public class MyContext : DbContext
{
    public MyContext(DbConnection existingConnection, bool contextOwnsConnection) 
        : base(existingConnection, contextOwnsConnection)
    { }


    public DbSet<Stuff> Stuff { get; set; }
}


using(var conn = new SqlConnection(asqlserverConnectionString))
            using (var db = new MyContext(conn, true))
            {
                var value = await db.Stuff.Where(s => s.xxx.Equals(primaryKey)).Select(s => new { s.BinaryContent } ).SingleOrDefaultAsync();
            }