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File Explorer not previewing pdf files since 25H2 update

Paul Nicholson 540 Reputation points
2025-10-15T08:07:37.1033333+00:00

Since installing the 25H2 update to Windows 11, the preview for pdf files is not working.

I just get the following message "The file you are attempting to preview could harm your computer. If you trust the file and the source you received it from, open it to view its contents"

I have tried everything to restore the preview without success.

Any help would be much appreciated!

Windows for home | Windows 11 | Files, folders, and storage

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  1. Joao Seabra 15 Reputation points
    2025-10-16T13:45:25.0033333+00:00

    Hi,

    I use Adobe Acrobat (Pro) to preview my files in explorer.

    Go to Adobe > Preferences > Security (Enhanced) and deselect 'Enable Enhanced Security' - you should be able to preview your PDF's in explorer.

    Not sure this is the right solution, but works for me. I need to preview documents for my work, no choice here since I updated to 25H2.

    Use this solution at your own risk.

    Regards

    2 people found this answer helpful.
  2. DavidW 10 Reputation points
    2025-10-16T20:49:04.93+00:00

    Go to Internet Options and set Security settings as noted below:

    1. Close File Explorer
    2. Open Internet Options from Search Bar
    3. Go to Security Tab.
    4. Click Local Intranet
    5. Click sites.
    6. Select Automatically detect
    7. Click Advanced
    8. Add the path where your files are saved, i.e. file://192.168.1.xxx. Click Add
    9. Click Close
    10. Click OK
    11. Click OK
    12. Restart File Explorer
    2 people found this answer helpful.
  3. Kirill P 25 Reputation points
    2025-10-17T15:05:57.5366667+00:00

    After applying this solution, Windows will stop showing the "security warning" when you try to open files downloaded to your Downloads folder.

    Step 1: Unblock all already downloaded PDF files. Open PowerShell as Administrator and run:

    Unblock-File -Path "C:\Users\admin\Downloads\*.pdf"

    Replace admin with the actual path where your files are downloaded. Usually, it's your user folder on drive C. You can check your exact user path by running this command in PowerShell:

    $home

    Step 2: Prevent Windows from setting the "file is blocked" flag for newly downloaded files. Open Registry Editor (Win + R > type regedit) and navigate to:

    Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\

    Create a new key named Attachments. Inside it, create a new DWORD (32-bit) value called SaveZoneInformation and set it to 1.

    Or paste this in PowerShell:

    New-Item -Path "HKCU:\Software\Microsoft\Windows\CurrentVersion\Policies\Attachments" -Force | Out-Null
New-ItemProperty -Path "HKCU:\Software\Microsoft\Windows\CurrentVersion\Policies\Attachments" -Name "SaveZoneInformation" -PropertyType DWord -Value 1 -Force | Out-Null

    Alternatively, you can do the same via Group Policy Editor (Win + R > type gpedit.msc): User Configuration > Administrative Templates > Windows Components > Attachment Manager > Do not preserve zone information in file attachments > Enabled

    Step 3: The same issue can happen when opening PDFs from shared network locations. In that case, do the following: Press Win + R, type inetcpl.cpl, and open the Security tab. Select Local intranet > click Sites > check Automatically detect intranet network. You can also click Advanced, then add the required network IP range manually — for example: 192.168.1.* > click Add.

    2 people found this answer helpful.
  4. Vivekanandan Tiwari 5 Reputation points
    2025-10-20T03:18:02.11+00:00

    Here is a simple solution that worked for me -

    in the file explorer, just disable this check box as shown in the image, this simply worked for me

    (This happened on windows 10 as well!)
    Screenshot 2025-10-20 084655

    2 people found this answer helpful.
  5. Paul L 15 Reputation points
    2025-10-20T13:17:35.33+00:00
    2 people found this answer helpful.
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