Strange error on one web server in our production environment: MissingMethod exception, though I don't think a method is missing

We're running a web application distributed across load balanced 3 web servers. The exact same code base & configuration is deployed across the 3 servers, and since about 1 hour ago I'm getting the following error on one of them, but not the other two.

System.InvalidOperationException: An error occurred when trying to create a controller of type 'XXX.Controllers.HomeController'. Make sure that the controller has a parameterless public constructor. ---> System.MissingMethodException: No parameterless constructor defined for this object.
   at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandle& ctor, Boolean& bNeedSecurityCheck)
   at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean fillCache)
   at System.RuntimeType.CreateInstanceImpl(Boolean publicOnly, Boolean skipVisibilityChecks, Boolean fillCache)
   at System.Activator.CreateInstance(Type type, Boolean nonPublic)
   at System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType)
   --- End of inner exception stack trace ---
   at System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType)
   at System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName)
   at System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory)
   at System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state)
   at System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state)
   at System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData)
   at Syst开发者_开发问答em.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

We are running this with ASP.NET MVC (with Output Caching), NHibernate (with NHibernate caching) & StructureMap. The cache is not shared, so each web server manages its own cache, though the cache dependencies are the same across the 3 servers.

I don't really know where to start describing what/where it could be going wrong or the circumstances, because it's so strange to me.

I've seen this once before about 2 weeks ago, but it went away on its own after about an hour and I haven't seen it since. Has anyone else seen an error like this before?

---

Well, it seems your HomeController is missing a parameterless constructor. Are you sure it has one? The default controller factory needs one to intialize your constructor.

Unless you are using your own ControllerFactory, in which case you need to register it during Application_Start:

protected void Application_Start()
{
     //other code

     ControllerBuilder.Current.SetControllerFactory(new MyCustomControllerFactory());
}

---

Assuming you're resolving controllers with structuremap, it may be your components are registered at the wrong place/time.

Are you registering components in Application_Start ?