CAN'T CHANGE FILE PERMISSIONS OR DELETE THEM AND I OWN THE COMPUTER!

Question

Explorer is regenerating thumbnails EVERY TIME I open a folder. Solution I found is to delete the thumbcache files so they can be regenerated.

I'm the owner and so administrator of this computer, so why does Windows tell me I need permission form the administrator to do this? I AM THE ADMINISTRATOR!!

Answer 1

Hi hpbgsd het,

Thanks for reaching out to Microsoft Q&A!

I know it can feel frustrating when Windows blocks you from managing files on your own computer, especially when you're literally the administrator. This happens because Windows was protecting some files from itself, not from you.

In Windows, File Explorer runs with standard user rights, even for admin accounts. Some files, like thumbcache files, are created and used by Windows so it cannot self‑elevate. Hence, the delete action is blocked with “need permission from the administrator” — it means the Elevated permission, which needs to be granted by you.

Now, going back to your thumbcache files, did you successfully remove them yet? I hope it works, but in case it doesn’t, I have some other suggestions you can consider checking out:

1 - Disk Cleanup

• Press Win + R > type cleanmgr > press Enter.
• Select your C: drive > Clean up system files > C: again
• In the list, check the box for Thumbnails > click OK > Delete Files.

2 -Take ownership and delete manually

• Open File Explorer and navigate to C:\Users\[YourUsername]\AppData\Local\Microsoft\Windows\Explorer
• Right-click the thumbcache file you want to delete > Properties.
• Go to the Security tab > Advanced > Owner then click Change
• Type administrators in the box > Check Names > OK.
• Check the box Replace owner on subcontainers and objects
• Apply the changes > go back in the Security tab > click Edit
• Select Administrators > check Full Control > Apply and OK.

3 - Use Command Prompt / PowerShell with admin rights

• Press Win + X > choose PowerShell / Terminal (Admin)
• Type: del /f /s /q /a %LocalAppData%\Microsoft\Windows\Explorer\thumbcache_*.db
• Press Enter > let it run and then restart your PC.

4 - Disable thumbnails via Registry

• Press Win + R > type regedit > press Enter to open Registry Editor
• Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced.
• Right-click in the right pane > New > DWORD (32-bit) Value:
  • Name: DisableThumbnailCache
  • Set its value to 1
  • Restart your computer.

Disclaimer: Generally, modifying registry subkeys or work group is intended for advanced users, administrators, and IT Professionals. It can help fix some problems, however, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For further protection, first check out How to back up and restore the registry in Windows - Microsoft Support 

I hope the answer above gives you the explanation for what you’re experiencing. Let me know if there’s anything not clear enough!

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Answer 2

Windows shows this message because of how permissions, locks, and User Account Control (UAC) work, even when logged on as an administrator.

Key points and what to do:

1. Administrator vs. elevated rights

• Being in the Administrators group does not mean every action runs with full admin rights all the time.
• With UAC enabled, Windows Explorer usually runs with standard-user rights. When trying to change protected files (like system caches), Windows may block the action or ask for elevation.
• In some cases, Explorer cannot elevate itself in-place, so it shows messages like “You need permission from an administrator,” even if the account is an administrator.

2. Files may be locked or have restrictive ACLs

• System files such as thumbcache or files under certain system locations can:
  • Be in use by another process (open handle), or
  • Have an Access Control List (ACL) that does not currently grant delete/modify rights to the user token Explorer is running under.
• Even administrators may need to explicitly take ownership and grant themselves permissions before deleting some files.

3. How UAC and Explorer change permissions

• When UAC is enabled and trying to access a folder without Read permissions, Explorer shows a dialog:
  • “You don't currently have permission to access this folder. Click Continue to permanently get access to this folder.”
• If Continue is selected and UAC can obtain administrative rights, a background elevated process modifies the folder’s permissions (ACL) to grant the user access, often Full Control in newer Windows versions.
• This is by design; Explorer does not run multiple instances with different security contexts in one session, so it changes ACLs instead of just running “as admin” for that one action.

4. When UAC is disabled

• If UAC is disabled, all programs run with full administrative rights for members of Administrators.
• However, if a folder or file ACL does not grant the user rights and the user does not have permission to change that ACL (for example, due to ownership or non-canonical ACL issues), Explorer cannot silently fix it and may still show permission errors.

5. Deleting protected or problematic files If a file or cache cannot be deleted via Explorer:

• Take ownership and grant permissions:
  • As an administrator, take ownership of the file/folder.
  • Then grant the account Full Control and delete the file.
• If the ACL is non-canonical or the UI tools cannot modify it, use command-line tools to rewrite the ACL.
• For files with problematic names (for example, trailing spaces or special characters), use tools that support the \\?\ path syntax and then delete via command line.

6. Special case: thumbcache / thumbs.db on network folders

• For network folders, thumbnail caching can keep files like thumbs.db open, preventing rename/delete operations and causing errors such as “folder or a file in it is open in another program.”
• A workaround is to disable thumbnail caching in hidden thumbs.db files via Group Policy or the equivalent registry setting:
  • Policy: User Configuration\Administrative Templates\Windows Components\Windows Explorer → Turn off the caching of thumbnails in hidden thumbs.db files → Enabled.
  • Registry: HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\Explorer → DisableThumbsDBOnNetworkFolders (REG_DWORD) = 1.

7. When files are otherwise inaccessible

• If a file is inaccessible due to a combination of ACL issues and problematic naming, use a tool such as Subinacl with the \\?\ path syntax to set ownership and permissions, then delete it from the command line.

In practice, for thumbcache/thumbnail issues:

• Close all Explorer windows.
• Optionally disable thumbnail caching on network folders (if applicable) as described above.
• Use an elevated tool (Command Prompt, PowerShell, or specialized utilities) to take ownership and grant Full Control on the cache files, then delete them.
• Reopen Explorer so Windows regenerates the caches.

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References:

• You can't delete a file or a folder on an NTFS file system volume
• Renaming a network folder in Windows 7 Explorer fails with "the action can't be completed..."
• When you select Continue for folder access in Windows Explorer, your user account is added to the ACL for the folder