2008 R2 Server - Error 0x800f0818 during SP1 Install

When I launch the SP1 update, installation fails with error 0x800f0818.

Here  are the step used to solve this issue:

1. I have downloaded following Microsoft Tool:


The tool runs and checks that everything is clean for an upgrade to SP1. 

2. If it doesn't fix anything, it just checks and leaves logs here:


3. If you see a number of fixed files at the top of the log: try to install Service Pack 1 again.

4. If you see anything under "Unavailable repair files": keep reading.

In second case if you get warning about corrupted file:

Package_for_KB2506014_RTM~31bf3856ad364e35~amd64~~ and Package_for_KB2506014_RTM~31bf3856ad364e35~amd64~~

5. From Microsoft download patch. Open a browser window and navigate to 

http://support.microsoft.com/kb/(number here)

and use an extraction utility like 7-Zip to extract the CAB files from the MSU installer and then again to extract the contents of the CAB files.

6. Copy the .mum and .cat files to "%windir%\Temp\CheckSUR\servicing\Packages" and run tool again