You may get the following error while installing a service pack or updates on Windows 2008 R2 (Error: 0x800f0818)

Checking Windows Servicing Packages
Checking Package Manifests and Catalogs
(f) CBS MUM Corrupt 0x00000000 servicingPackagesPackage_for_KB2393802_RTM~31bf3856ad364e35~amd64~~6.1.1.1.mum  Expected file name Microsoft-Windows-Foundation-Package~31bf3856ad364e35~amd64~~6.1.7600.16385.mum does not match the actual file name
Checking Package Watchlist
Checking Component Watchlist
Checking Packages
Checking Component Store
Summary:
Seconds executed: 98
Found 1 errors
CBS MUM Corrupt Total count: 1
Unavailable repair files:
servicingpackagesPackage_for_KB2393802_RTM~31bf3856ad364e35~amd64~~6.1.1.1.mum
servicingpackagesPackage_for_KB2393802_RTM~31bf3856ad364e35~amd64~~6.1.1.1.cat

To fix the issue, you must copy files Package_for_KB2393802_RTM~31bf3856ad364e35~amd64~~6.1.1.1.mum and Package_for_KB2393802_RTM~31bf3856ad364e35~amd64~~6.1.1.1.cat to folder C:Windowsservicing

You can find these files in other windows installations. Then you can try to install SP1. If the problem persists, you can run the command from elevated cmd:

sfc /scannow

After that, everything will work fine!