How to allow aspx files

I have a website running Episerver CMS hosted in an Azure webapp.

My goal is to display a 404 page when a user goes to www.mysite.com/test.aspx, This works locally on my IIS site, but when deployed to Azure instead of a 404 I get a 500 exception:

System.Web.HttpException (0x80004005): The file '/test.aspx' does not exist. at System.Web.UI.Util.CheckVirtualFileExists(VirtualPath virtualPath
 at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate
 at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate
 at System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound
 at System.Web.Compilation.BuildManager.CreateInstanceFromVirtualPath(VirtualPath virtualPath, Type requiredBaseType, HttpContext context, Boolean allowCrossApp
 at System.Web.UI.PageHandlerFactory.GetHandlerHelper(HttpContext context, String requestType, VirtualPath virtualPath, String physicalPath
 at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute(
 at System.Web.HttpApplication.<>c__DisplayClass285_0.<ExecuteStepImpl>b__0(
 at System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step
 at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Any recommendations?