How to set custom access denied pages in SharePoint 2013?

Question

Hi everybody,
in SharePoint 2010 custom access denied or other error pages could be easily set by setting the new path to the webapp-properties by using webApp.UpdateMappedPage. In SharePoint 2013 this seems to be ignored. The MSDN-entry seems to be out of date and just
copied from SharePoint 2010:
http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.administration.spwebapplication.updatemappedpage.aspx
A possible workaround could be writing a HttpModule that checks the requested url for accessdenied.aspx and redirects to a custom page but there must be another more best practice way to achieve this behaviour??

Answer 1

I found a workaround to redirect to a custom access denied page but I'm not happy with it.
I created a HttpModule which uses static method SPCustomRedirect.RegisterRedirectHandler to register a class inheriting ISPCustomRedirectHandler to the current HttpContext. In this class there is a method GetRedirectUrl that returns the path to my custom
access denied page.
Now at last a value must be written to the HttpRequest.Querystring named "CustomRedirect". But to add something to the QueryString-NameValueCollection I must use reflection to make it writable because it's readonly. After setting the value, I reset the property
to readonly.
For clearness, I post the code-snippet from the HttpModule below:
HttpRequest request = HttpContext.Current.Request;
NameValueCollection QS = request.QueryString;
QS = (NameValueCollection)request.GetType().GetField("_queryString", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(request);
PropertyInfo readOnlyInfo = QS.GetType().GetProperty("IsReadOnly", BindingFlags.NonPublic | BindingFlags.Instance);
readOnlyInfo.SetValue(QS, false, null);
QS["CustomRedirect"] = "CustomAccessDenied";
readOnlyInfo.SetValue(QS, true, null);
SPCustomRedirect.RegisterRedirectHandler("CustomAccessDenied", new CustomAccessDenied());
This is the redirectHandler-class I register in the last line:
public class CustomAccessDenied : ISPCustomRedirectHandler
public string GetRedirectUrl(string key)
string serverRelativeUrl = string.Empty;
var ctx = HttpContext.Current.Items["DefaultSPContext"];
if (ctx != null)
serverRelativeUrl = ((SPContext)ctx).Web.ServerRelativeUrl;
if (serverRelativeUrl.Equals("/"))
serverRelativeUrl = string.Empty;
return string.Format("{0}/_layouts/15/myCode/CustomAccessDenied.aspx", serverRelativeUrl);
This works fine but I really don't like the need to add a value to the querystring by reflection or the need to do this for every page-request...
What's your opinion for this?