Windows Vista Service Pack Won't Install

Symptom:

Microsoft Windows Vista Service Pack 2 is downloaded. It goes through the whole installation procedure without error, reboots, gets to 100% of Stage 3 of 3, and then announces Service Pack did not install. Reverting changes. On the next login it exudes a dialog box saying Installation was not successful. Unspecified error. Details: Error: E_FAIL(0x80004005).

A forum poster reports the same problem with SP1, and I wouldn't be too surprised to find the same problem with XP service packs.

What's going on:

In this forum posting look for Sekim's contribution. He refers to KB971204 which suggests: Look in %windir%\Logs\CBS\CBS.log ; you may see that C:\Windows\bfsvc.exe reports Failed to get system partition! Last Error = 0x3bc3. If third party disk management tools are used to "clone" discs or partitions, the SP2 installer will be unable to uniquely identify the correct system boot files. (This is my situation.)

In other words, the service pack replaces the Windows kernel and the bootloader (equivalent of grub), and it will need to fill the block numbers into the boot sector of the partition containing the bootloader. If it cannot identify the partition it will be unable to do this last critical step of installation. It should check the partition at the beginning, but it doesn't.

How to fix:

Make the possibly confusing drives disappear (impossible for me) or do a clean installation. Various successful workarounds mentioned in forum postings include:

• If you're using Grub, it doesn't care about the active flag, but Windows does. NRWickert marked the Windows partition as active and removed that flag from Linux, installed SP1, then put the active flags as they had been. Likely Windows could have just stayed active, and there's a fairly good chance that this strategy would have been effective for me.

• Some people do weird things in the registry that provoke this error. A clean installation will take care of such problems. A clean installation will also make the Windows partition active.

• One anonymous person has Windows and Linux on separate physical discs. He changed the boot order in the BIOS to boot from the Windows disc, and that made SP2 install. Another person used the BIOS to actually deactivate all but the Windows disc.

• My machine started out dual booting Windows and Linux, but I installed Xen and ran Windows in a virtual machine. To avoid reinstalling Windows I booted both the host and the guest off the same master boot record and grub (bootloader) blocks, using their separate partitions.

  To get SP2 to install I created a partition for the new Windows instance and, following what seems to be normal practice with virtual machines, I let the Windows installer partition it as if it were an entire disc. Thus, there could be no confusion which partition's boot sector needed to have the block list filled in. In addition, it became impossible to accidentally boot Linux in the guest (simultaneous with the host), or to boot Windows on the bare metal. I should not have been so reluctant to reinstall Windows.