Autofac Losing Registrations on Web.Config Edit

Question

I have a layered web application that I built with ASP.NET MVC 4, WebAPI and some other components. I'm using the latest release of Autofac 2.6.2.859 as my DI container along with the MVC and WebAPI integrations. I have autofac modules setup in my different layers and I'm using the new RegisterAssemblyModules to scan the AppDomain assemblies for the various modules.

On startup every works great. When I edit the web.config file and the application warms up, my registrations are lost. I get a DependencyResolutionException -

None of the constructors found with 'Public binding flags' on type 'My.Class.Name' can be invoked with the available services and parameters:

So my registrations are not being reloaded. Does anyone know how to address this issue? Should I put my initialization code somewhere else other than Application_Start() ?

UPDATE

Here's what my code looks like

 public static class IoC
{
    public static void Configure()
    {
        var builder = new ContainerBuilder();
        var assemblies = AppDomain.CurrentDomain.GetAssemblies();

        //Assembly Modules            
        builder.RegisterAssemblyModules<NSUTriviaModuleBase>(assemblies);

        // Register API controllers using assembly scanning.
        builder.RegisterControllers(assemblies);

        // Register API controllers using assembly scanning.
        builder.RegisterApiControllers(assemblies);

        var container = builder.Build();
        // Set the dependency resolver implementation.
        var resolver = new AutofacWebApiDependencyResolver(container);

        GlobalConfiguration.Configuration.DependencyResolver = resolver;
        DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
    }
}

Interesting - are you running this at debug time, e.g. in Cassini or IIS Express, or is this something you're doing in prod? :) — Nicholas Blumhardt, Jun 15 '12 at 15:50
It is running in debug mode on a remote staging server with IIS 6 and .NET 4.0. It works fine on IIS 7.5 Express locally. Errors only arise when there's a recycle. — cecilphillip, Jun 15 '12 at 19:02
Are you able to set any tracing/logging to examine the states of the DependencyResolvers when the error occurs? Are they both still the Autofac ones? — Jim Bolla, Jun 16 '12 at 02:36
We've tried the solution from Alex Meyer-Gleaves but it still doesn't work. We are using IIS Express/VS2012. At least we can reproduce it reliably with a web.config edit! — SturmUndDrang, May 30 '13 at 08:36

Alex Meyer-Gleaves · Accepted Answer · 2012-06-20T08:19:23.567

I think the problem is that all assemblies are loaded into the AppDomain when the application first starts, but when the AppDomain is recycled by IIS the assemblies are then only loaded on demand.

Try using the GetReferencedAssemblies method on System.Web.Compilation.BuildManager to get a list of the referenced assemblies instead.

var assemblies = BuildManager.GetReferencedAssemblies().Cast<Assembly>();

That should force the referenced assemblies to be loaded into the AppDomain immediately making them available for module scanning.

Autofac Losing Registrations on Web.Config Edit

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