"You do not have permission to access this file" - BUT I AM THE ONLY USER?!

Kin_

Okay, this is driving me crazy. I'm trying to open a folder on my external hard drive and Windows is telling me I don't have permission. This is my personal laptop, I am the admin, and it’s my own damn drive. Why is my computer locking me out of my own stuff? Send help before I throw this laptop out the window.

Leo17

Kin_

Classic issue. Did you use this external drive on a different computer before? That's usually the cause: the files have ownership tied to a user account that doesn't exist on your current machine.

Try this:

Right-click the folder → Properties → Security tab

Click Advanced

At the top, click "Change" next to Owner

Type your username or click "Advanced" to find it

Check "Replace owner on subcontainers and objects"

Click Apply

Then you need to add yourself to the permissions list:

Back in Security tab, click Edit

Add your username, give it Full Control

Apply

Let me know if that works.

Lisa

Leo17

To explain what's actually happening here, this is a fundamental aspect of how NTFS security works that Microsoft never properly explains to end users.

Every file and folder in NTFS has an Access Control List (ACL) that contains Access Control Entries (ACEs). Each ACE specifies a Security Identifier (SID) - not a username, but a unique identifier generated when a user account is created. When you create a file on Computer A, your SID gets embedded into that file's ACL as the owner and as having Full Control.

The problem is that SIDs are local to each Windows installation (unless you're using domain accounts). So when you plug that drive into Computer B, Windows looks at the ACL, sees a SID it doesn't recognize (because that SID was generated on Computer A's user account), and says "I don't know who this is, so I'm going to deny access by default."

Being an "administrator" doesn't automatically grant you access to files owned by other SIDs. Administrators have the right to take ownership, but they don't automatically have ownership. This is by design, it's a security feature to prevent admins from casually accessing user data without explicitly taking ownership first.

Kin_

Leo17 I tried that but when I click "Change" for the owner, it says "You do not have permission to view or edit this object's permission settings." How am I supposed to change the owner if I can't even view the permissions?? This is insane.

Hebe22

Lisa

That's mostly correct, but there's an important distinction you're glossing over. Administrators don't just have the "right" to take ownership - they have the SE_TAKE_OWNERSHIP_NAME privilege which allows them to assign themselves as owner without having any existing permissions on the object. This is different from the "Take Ownership" permission in the ACL, which is a granular permission that can be granted to non-admins.

Also, the default behavior isn't "deny by default", it's that when the SID doesn't resolve to a known user, Windows can't evaluate the ACE, so the access check fails. The ACE isn't evaluated as a deny, it's just not matchable. This is why you sometimes see "Account Unknown" in the Security tab.

And importantly, this only applies to files that have explicit permissions. If the file only has inherited permissions and the parent folder's ACL resolves correctly, access would work. The issue here is almost certainly explicit permissions set on the folder itself.

RoseLO

Ah yes, the "I'm the admin so I should own everything" fallacy. Welcome to Windows security, where being admin means you can take ownership, not that you already have it.

OP, quick question, did you buy this drive new, or did it "come from a friend" or "used to belong to my old laptop"? Because 99% of the time, this error means someone else's Windows account created those files, and now Windows is doing exactly what it's designed to do - protecting data from unauthorized access.

The irony is that you're complaining about a security feature that would prevent someone else from stealing your data if they plugged your drive into their computer. But when it happens to YOU, suddenly it's "my own damn drive."

Anyway, @#2's steps are correct. Just make sure you run them as administrator, some folders won't let you change ownership unless you elevate. Also, if there's a lot of subfolders, this can take forever. Patience.

Kin_

RoseLO Yes the drive was from my old laptop that died. I just want my photos back.