Merge with 4.11.5

src/Umbraco.Web.UI/config/umbracoSettings.Release.config

@@ -254,4 +254,17 @@
     trySkipIisCustomErrors="false">
   </web.routing>
 
+  <!-- 
+    web.routing
+      @trySkipIisCustomErrors
+        Tries to skip IIS custom errors.
+        Starting with IIS 7.5, this must be set to true for Umbraco 404 pages to show. Else, IIS will take
+        over and render its build-in error page. See MS doc for HttpResponseBase.TrySkipIisCustomErrors.
+        The default value is false, for backward compatibility reasons, which means that IIS _will_ take
+        over, and _prevent_ Umbraco 404 pages to show.
+  -->
+  <web.routing
+    trySkipIisCustomErrors="false">
+  </web.routing>
+
 </settings>

src/Umbraco.Web/WebBootManager.cs

@@ -95,6 +95,9 @@ namespace Umbraco.Web
 
             base.Complete(afterComplete);
 
+            //Now, startup all of our legacy startup handler
+            ApplicationEventsResolver.Current.InstantiateLegacyStartupHanlders();
+
             return this;
         }