Installation of Windows 7/2008 R2 Service Pack may fail with error 0x800f0a12 if access to the BCD was denied during installation, which is required during the installation of the service pack. This can occur if the volume automount policy was set to disabled, or, in rarer cases, if the BCD database is corrupt or missing, or if something is wrong with the boot partition (where the bootloader lives).

Open an elevated command prompt, and run DISKPART.

Enable the automount policy:

DISKPART> automount enable

Restart the server, and try installing the service pack again.

If the above did not resolve the issue, there may be a problem with the boot partition.

Make sure the partition is mar  ...