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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

51 answers

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  1. ShellyS 5 Reputation points
    2025-10-21T17:12:35.63+00:00

    Another shining example of Microsoft's heavy hand. They "opt-in" you by default and say they told you about it (buried in some big release note somewhere). You're left with 100's of angry users filling up your voicemail and ticket queue wondering why "it's broke now". Thanks Microsoft I didn't have anything else to do today.

    1 person found this answer helpful.
  2. Jerimy Orr 5 Reputation points
    2025-10-21T17:41:56.0266667+00:00

    I had the same issue as InchCreations, but once I checked the Unblock option box, saved then opened the file, moving forward I could preview it. It's incumbering but effective, for now.

    1 person found this answer helpful.
  3. Johnny 5 Reputation points
    2025-10-22T14:30:52.32+00:00

    @Jess Iannone Your suggestion posted 2025.10.21 worked for me too (uncheck "Show preview handlers in preview pane" in file explorer > Folder Options > View)

    However there are now other file types I can't preview such as the contents of .TXT files.

    That said I view .PDF much more often so I'm goin to use that for now until the issue is fixed.

    Thanks :)

    1 person found this answer helpful.
  4. Antoine Knight 5 Reputation points
    2025-10-22T14:56:55.9733333+00:00

    We have solved this issue in our company by changing the security setting in "Internet Options" in control panel.

    Screenshot 2025-10-22 105150

    Once there go to trusted sites and place the path of the folder that has the docunements you want to view.

    Screenshot 2025-10-22 105406

    Make sure you click "Add" and uncheck the box.

    Screenshot 2025-10-22 105541

    1 person found this answer helpful.
  5. Sunny Surella 5 Reputation points
    2025-10-24T01:19:43.82+00:00

    Below solution steps worked for me:

    A) Currently on Windows 11, version 25H2 for x64-based Systems (KB5070773) (26200.6901).
    B) In Defender:

    User's image

    First-

    1. Check if you are missing PreviewHandlers Registry Key, if yes then use below:

    Method 1) Fix: Recreate the Missing PreviewHandlers Registry Key

    Step 1. Open Registry Editor

    1. Press Win + R, type regedit, and press Enter

    Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer

    Step 2. Create the Missing KeyStep 2. Create the Missing Key
    Right-click Explorer → New → Key.

    Name it exactly: PreviewHandlers

    Step 3. Restore Default Preview Handler Entries Inside PreviewHandlers, create the following String Values (REG_SZ) — you can copy and paste both the names and values exactly:

    Microsoft Office Preview Handler
    {65235197-874B-4A07-BDC5-E65EA825B718}
    Microsoft Office Preview Handler
    {65235197-874B-4A07-BDC5-E65EA825B718}
    Microsoft PDF Preview Handler
    {DC6EFB56-9CFA-464D-8880-44885D7DC193}
    Microsoft Word Preview Handler
    {84F66100-FF7C-4fb4-B0C0-02CD7FB668FE}
    Microsoft Excel Preview Handler
    {00020827-0000-0000-C000-000000000046}
    Microsoft PowerPoint Preview Handler
    {65235197-874B-4A07-BDC5-E65EA825B718}
    Microsoft Outlook Mail Preview Handler
    {A776EDEF-81C0-4A3C-BE0A-46E36A9B8E2D}
    Text Preview Handler
    {1531d583-8375-4d3f-b5fb-d23bbd169f22}
    Image Preview Handler
    {FFE2A43C-56B9-4bf5-9A79-CC6D4285608A}

    (You don’t need all of them; adding the Text, PDF, and Image handlers is usually enough.)

    1. It should look like below screenshot: User's image

    Step 4. Restart Explorer

    Either reboot, or open Command Prompt and run:

    taskkill /f /im explorer.exe

    start explorer.exe

    Then test your preview pane again. If it did not work, then use below solution as well:

    I also used Mark Zuber's suggestion and used below method:

    Method 2)

    Automate It for Multiple Common Folders

    If you want this to apply to multiple folders, use a script like this:
    Open Notepad and paste below code:

    User's image

    $folders = @(

    "$env:USERPROFILE\Downloads",

    "$env:USERPROFILE\Documents",

    "$env:USERPROFILE\Desktop"

    )

    foreach ($folder in $folders) {

    if (Test-Path $folder) {Write-Host "Unblocking files in $folder..." Get-ChildItem -Path $folder -Recurse -ErrorAction SilentlyContinue | Unblock-File

    }

    }

    Write-Host "✅ All files have been unblocked successfully."

    Save it as UnblockFiles.ps1, then run it once as Administrator (right-click → Run with PowerShell). This clears MOTW tags from typical folders where downloaded content lives.

    I hope it will help everyone until Microsoft has a fix for it. The above may not be a proper solution, and may not work for everyone. But is a workaround for now and worked for me.

    1 person found this answer helpful.

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