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Deistic's avatar
Deistic
Copper Contributor
Jan 03, 2025

Unknown Account: SiD

So i know many people have an issue where they re-install windows or for whatever reason they encounter an "Unknown Account: SID"  under their security tabs.

Please note that you can always use lusrmgr  to check on the SID code to see what that account actually IS.


As you can see here, i have "Account Unknown" (S-1-15-3-6)

Here in the lusrmgr it clearly shows that that SID leads to "Your music library"

This means it is safe to delete, as it is NOT a user or group that would need permission for the users folder.
Simply "Change permissions" by clicking the edit and accepting the UAC.


No adverse side effects, and this is also a good way to make sure you are able to delete a permission, and know what it is.  

Hope i helped anyone who has these "Multiple SIDs".

This is how i removed mine safely, they arent always actually "User accounts"

  • AxelVortex's avatar
    AxelVortex
    Iron Contributor

    If you encounter an "Unknown Account: SID" under security tabs after reinstalling Windows, you can use lusrmgr to identify what it is. For example, a SID might link to something like "Your music library," not a user account. In such cases, it's safe to delete by changing permissions and accepting the UAC prompt. No adverse effects—this helps clean up unnecessary entries safely!

  • Holaway's avatar
    Holaway
    Steel Contributor

    If you see an "Unknown Account: SID" under the security tab after reinstalling Windows, it’s usually safe to remove. Use lusrmgr to check what the SID corresponds to—for example, a library or unused system reference, not an actual user account. Once confirmed, you can safely delete it by editing permissions and accepting the UAC prompt. This ensures no adverse side effects while keeping your system clean.

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