1

I manually created a restore point in Windows 8.1. It was visible in the list of points to restore to.

Later on, there are no restore points listed. There is plenty of disk space available and allocated for restores but it appears that they have been deleted. This is pretty dangerous, for example if you make a restore point before changing something major and then lose it in the interim.

Why does this happen?

2

This is due to dual-booting with an earlier version of Windows which does not recognise the restore point format and deletes it (!). In my case I was dual-booting Windows 8.1 with Windows XP but other combinations are possible.

This issue can be worked around by disabling mounting of the newer operating system's disk/partition from the older operating system by setting the registry key:

HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices\Offline REG_DWORD "\DosDevices\D:" -> 1

D: is the name/mount point of the newer disk/partition when running the older operating system. You can obviously no longer access the new disk from the old operating system in this case but could do so through a third disk/partition or other media. The new operating system is still able to access the old disk/partition.

Full information in the knowledge base article. It also mentions working around this problem using disk encryption.

  • This is a good answer. What is more likely is that Windows XP and Windows 8.1 were fighting over the partition since both create have the capability to create recovery points. – Ramhound Sep 18 '15 at 11:13
  • Nope, definitely this. XP has system restore disabled, and they are separate partitions/disks. See the linked KB article, it's a known issue. – Sam Brightman Sep 18 '15 at 12:22

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