Unknown User as Owner

Hi guys, I have a peculiar issue with an unknown Owner of a folder.
To be more precise, its on my external Drive, in a folder called My Backups.
I use Acronis on a disk to perform backups. Acronis is not installed.
Path: ‪L:\My backups\Windows 10 Pro (C)
Owner: S-1-5-21-4052398736-303783888-1690356549-1002



I entered "net users" in cmd.exe & the above account is not listed there.
I have a built-in Administrator-, Guest-, Default-, WDAGUtility- and my current account.



The above Owner number does not appear in Regedit either.



Nor does it appear in Computer Management --> Local User Groups...

So who could this be, and is it safe to set it as a member of Administrators?

Ok, slight change of plans. I was going to post the above when I did a closer inspection of other folders & files in L:\My backups. ‪L:\My backups\Recovery Partition has yet another unfamiliar Owner!



Owners of the 5 backup folders:
‪L:\My backups\Data HP (E): Administrators (HP-PAVILION\Administrators)
‪L:\My backups\FACTORY_IMAGE (D): Administrators (HP-PAVILION\Administrators)
‪L:\My backups\Recovery Partition: S-1-5-21-2524673758-597247510-780583039-1001
‪L:\My backups\Windows 7 Pro: S-1-5-21-4052398736-303783888-1690356549-1002
L:\My backups\Windows 10 Pro (C): S-1-5-21-4052398736-303783888-1690356549-1002

So I have to ask again, who could this be, and is it safe to set them all as a member of Administrators?

witten1972 said:

Hi guys, I have a peculiar issue with an unknown Owner of a folder...
Owner: S-1-5-21-4052398736-303783888-1690356549-1002

So who could this be, and is it safe to set it as a member of Administrators?

How many PCs has this external drive been used with? An unknown user like this is typical of a folder that was created by a user on another PC. As this PC has no record of that user it just displays the unique SID. The usual fix is to take ownership of the folder, or assign it to another known user on this PC.

The other way to end up with unknown users is to reinstall Windows. Even if you use the same user name again, the SID of the old user will no longer exist on this PC.

witten1972 said:

Owners of the 5 backup folders:
‪L:\My backups\Data HP (E): Administrators (HP-PAVILION\Administrators)
‪L:\My backups\FACTORY_IMAGE (D): Administrators (HP-PAVILION\Administrators)
‪L:\My backups\Recovery Partition: S-1-5-21-2524673758-597247510-780583039-1001
‪L:\My backups\Windows 7 Pro: S-1-5-21-4052398736-303783888-1690356549-1002
L:\My backups\Windows 10 Pro (C): S-1-5-21-4052398736-303783888-1690356549-1002

So I have to ask again, who could this be, and is it safe to set them all as a member of Administrators?

I'd assign ownership of those last three to Administrators.

Change Owner of File, Folder, Drive, or Registry Key in Windows 10

Hi Bree, thanks for stepping up to address this issue.
As far as I know my External Drive has only been used on my PC.

I could try to implement your suggestion and take Ownership of those Folders.
The "Take Ownership" link is present in my right click menu, but I'm currently logged in with my Microsoft account, so perhaps it would be better if I went Properties --> Security --> Advanced & set the Owner to Administrators, no?!

Although my mind is bugged with a new question now.
If I change the Owner & later on I have to restore a backup (Acronis on a CD) won't I encounter problems then?

It's permissions rather than ownership that could potentially cause problems. I'm assuming (as I don't use Acronis) that it will run as administrator when you use it. If the Administrators group has full control then there should be no problems.

I created a new folder to show a screenshot when I just added the Administrator and where there are two check boxes to choose from. Do I need to check them both?

I'd tick the top one, it replaces ownership on all sub-folders and files. Do not click the Disable Inheritance button, inheritance should mean that permissions you set for that folder will apply to sub-folders and files.

Well, I just checked both boxes a minute before your reply
To be absolutely safe I'll create new backups...

Thanks for assistance Bree, much appreciated!

That second box replaces all permissions on sub-folders and files with those of the parent folder, should be any problem.

Bree (or anyone else) do you know of a way to scan all my Drives to find orphaned Owners?

Like these:
S-1-5-21-2524673758-597247510-780583039-1001
S-1-5-21-4052398736-303783888-1690356549-1002