Exception occuring at runtime, cannot point cause
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I'm getting this strange error returned from the server:

>A public action method 'SelectGroup' was not found on controller 'MySite.Controllers.ProductController'

However, `SelectGroup` _is_ a public action method in the `ProductController` class. As a matter of fact, calling `/Product/SelectGroup` just works most of the time, I just see this error being logged a few times a day.

__What can cause this error in this case?__


>System.Web.HttpException (0x80004005): A public action method 'SelectGroup' was not found on controller 'MySite.Controllers.ProductController'. at System.Web.Mvc.Controller.HandleUnknownAction(String actionName) at System.Web.Mvc.Controller.ExecuteCore() at System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) at System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) at System.Web.Mvc.MvcHandler.<>c__DisplayClass8.b__4() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass1.b__0() at System.Web.Mvc.Async.AsyncResultWrapper.<>c__DisplayClass8`1.b__7(IAsyncResult _) at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`1.End() at System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) at System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)