Installation of Visual Studio 2012 Update 3 fails with error ‘Unable to locate package source’

I recently installed Visual Studio 2012 and got the following error when trying to start it:

In order to fix this issue, I had to additionally install the Update 3 for Visual Studio 2012. You can do that by going in VS2012 to Tools => Extensions and Updates => Updates => Product Updates or by downloading it at http://support.microsoft.com/kb/2835600/en-us.

Installing Update 3 didn’t go as smooth as I have expected. The following packages were missing:

• windows app certification kit x64-x86_en-us
• windows app certification kit native components-x64_en-us

To fix this issue, you can download these from:

http://go.microsoft.com/fwlink/?LinkId=283370&clcid=0×409
http://go.microsoft.com/fwlink/?LinkId=283372&clcid=0×409

Start the Update 3 installer again and select repair. When it asks for these files, point it to the path where you downloaded the files. The installation should proceed after this and finish successfully.