When you install ”Application Catalog web service point” and ”Application Catalog website point” in SCCM 2012 you get 404 Error when browsing http://SCCMserver/CMApplicationCatalog. To fix this you need to enable/activate .Net 4
For example, on a 64-bit computer that runs the .NET Framework version 4.0.30319, run the following command:
%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe –i –enable