“A type load exception has occurred.” using DbContext with MySql connector with Mono

Question

I am trying to use the MySQL Database with the Entity Framework Version 4.1.0.0 and Mono 2.11.4 in a ASP.NET MVC 3 Project.

On my Local Windows system everything works great but when I publish it to my Ubuntu 12.04 LTS System I get a lot of errors.

First I get:

Could not load type 'System.Data.Entity.Infrastructure.DbUpdateException' from assembly 'EntityFramework, Version=4.1.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

when I press F5 I get different errors every time the page refreshes:

Could not load type 'System.Data.Entity.Infrastructure.DbUpdateConcurrencyException' from assembly 'EntityFramework, Version=4.1.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
Could not load type 'System.Data.Entity.Infrastructure.DbCompiledModel' from assembly 'EntityFramework, Version=4.1.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
Could not load type 'System.Data.Entity.Infrastructure.ReplacementDbQueryWrapper`1[TElement]' from assembly 'EntityFramework, Version=4.1.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
Could not load type 'MySql.Data.VisualStudio.Editors.SqlEditor' from assembly 'MySql.VisualStudio, Version=6.6.4.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d'.
Could not load type 'MySql.Data.VisualStudio.WebConfig.WebConfigDlg' from assembly 'MySql.VisualStudio, Version=6.6.4.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d'.
A type load exception has occurred.

The last error occurred when I try to use the database with this code:

using (var db = new DefaultContext())
{
    db.Persons.Add(new Person() { Name = "hallo", Address = "bllaaa" });
    db.SaveChanges();

    var persons = db.Persons.ToList();
    return View(persons);
}

Did anybody have a similar problem and solved it? I do not know what to do.

P.S.: I use Code First Migration

thomasjo thomasjo · Accepted Answer · 2012-11-20T22:45:42

From my understanding, Mono is bundling the open source version of Entity Framework, which is essentially yet-to-be-released v6.

http://weblogs.asp.net/scottgu/archive/2012/07/19/entity-framework-and-open-source.aspx

So it would seem you can't target EF v4.x, since the code has likely undergone major changes. Although, if you discover that the seemingly missing types are still there, you could attempt to work around the issue with an assembly redirect (just search for bindingRedirect).

“A type load exception has occurred.” using DbContext with MySql connector with Mono

2 Answers