In SharePoint 2010 I used
Set-SPCustomLayoutsPage -Identity AccessDenied (...) for adding my custom Access Denied page. When I do this in SharePoint 2013 it does not take effect. If I run Get-SPCustomLayoutsPage the field has been updated, but it still redirects to the standard 401 page.
Seems like others are experiencing the same. https://stackoverflow.com/questions/15949794/sharepoint-2013-custom-pages
Has anyone been able to set custom pages?