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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. Jam Z 0 Reputation points
    2025-10-17T21:07:50.85+00:00

    This error appeared following the security update. My google drive files could not be previewed.

    Few things to try to fix it from ChatGPT that worked for me:

    1: Remove the “Internet Zone” tag for all Google Drive files

    You can safely delete the Mark-of-the-Web tag from your Google Drive folder so previews work normally.

    Run PowerShell as Administrator, then paste this:

    Get-ChildItem "G:\My Drive" -Recurse | Unblock-File

    Replace G:\My Drive with your actual Google Drive path.

    1. (Adobe users)

    Open Adobe Acrobat Reader.

    Go to Edit → Preferences → Security (Enhanced).

    Uncheck Enable Protected Mode at startup (you can re-enable later).

    1. Restart File Explorer and test again.
    2. Add Google Drive’s mount path to Windows’ Trusted Locations

    Open Control Panel → Internet Options.

    Go to Security → Local intranet → Sites → Advanced.

    Click Add, and add:

    file://localhost/G:\

    (Replace G:\ with your actual Google Drive letter — check in File Explorer.)

    Click Close → OK → Apply.

    Hope this helps

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  2. Trung Nguyễn Thành 5 Reputation points
    2025-10-18T16:58:37.7066667+00:00

    Here are the English translations for the solutions provided:

    Solution 1: Registry Edit (Recommended) This procedure will configure Windows not to save zone information (Mark of the Web) for new file attachments.

    ⚠️ Warning: Editing the Registry incorrectly can cause system errors. Proceed with caution.

    Press Win + R to open the Run dialog box.

    Type regedit and press Enter. Click Yes if the User Account Control window appears.

    Navigate to the following key in the Registry Editor:

    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies

    Create a New Key:

    Right-click on the Policies key, select New -> Key.

      Name the new key __`Attachments`__.
  
  __Create a New DWORD Value:__
  
     Right-click on the newly created __`Attachments`__ key, select __New__ -> __DWORD (32-bit) Value__.
     
        Name the new value __`SaveZoneInformation`__.
        
        __Modify the Value:__
        
           Double-click on __`SaveZoneInformation`__.
           
              Ensure the __`Value data`__ is set to __`1`__.
              
                 Click __OK__.
                 
                 __Close the Registry Editor__ and __Restart your computer__ to apply the changes.

    After restarting, new PDF files downloaded or created should no longer trigger the preview error.

    Solution 2: Disable via Group Policy Editor (Applies to Windows Pro/Enterprise only) If you are using Windows Pro or Enterprise edition, you can achieve the same result through the Local Group Policy Editor:

    Press Win + R, type gpedit.msc and press Enter.

    Navigate to:

    User Configuration
-> Administrative Templates
-> Windows Components
-> Attachment Manager

    Find the setting "Do not preserve zone information in file attachments".

    Double-click this setting and select Enabled.

    1. Click Apply and OK.

    Restart your computer to apply the changes.Here are the English translations for the solutions provided:

    Solution 1: Registry Edit (Recommended) This procedure will configure Windows not to save zone information (Mark of the Web) for new file attachments.

    ⚠️ Warning: Editing the Registry incorrectly can cause system errors. Proceed with caution.

    Press Win + R to open the Run dialog box.

      Type __`regedit`__ and press __Enter__. Click __Yes__ if the User Account Control window appears.
  
     Navigate to the following key in the Registry Editor:
     
     ```yaml
     HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
     ```
     
        __Create a New Key:__
        
              Right-click on the __`Policies`__ key, select __New__ -> __Key__.
              
                    Name the new key __`Attachments`__.
                    
                       __Create a New DWORD Value:__
                       
                             Right-click on the newly created __`Attachments`__ key, select __New__ -> __DWORD (32-bit) Value__.
                             
                                   Name the new value __`SaveZoneInformation`__.
                                   
                                      __Modify the Value:__
                                      
                                            Double-click on __`SaveZoneInformation`__.
                                            
                                                  Ensure the __`Value data`__ is set to __`1`__.
                                                  
                                                        Click __OK__.
                                                        
                                                           __Close the Registry Editor__ and __Restart your computer__ to apply the changes.
                                                           
                                                           After restarting, new PDF files downloaded or created should no longer trigger the preview error.
                                                           
                                                           Solution 2: Disable via Group Policy Editor (Applies to Windows Pro/Enterprise only)
                                                           If you are using Windows __Pro__ or __Enterprise__ edition, you can achieve the same result through the Local Group Policy Editor:
                                                           
                                                              Press __Win + R__, type __`gpedit.msc`__ and press __Enter__.
                                                              
                                                                 Navigate to:
                                                                 
                                                                 ```haskell
                                                                 User Configuration

    -> Administrative Templates -> Windows Components -> Attachment Manager ```

                                                                        Find the setting __"Do not preserve zone information in file attachments"__.
                                                                    
                                                                       Double-click this setting and select __Enabled__.
                                                                       
                                                                          Click __Apply__ and __OK__.
                                                                          
                                                                             __Restart your computer__ to apply the changes.
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  3. Vivekanandan Tiwari 10 Reputation points
    2025-10-20T03:20:03.47+00:00

    Screenshot 2025-10-20 084655

    Disabling this option worked for me.,

  4. Pro450 10 Reputation points
    2025-10-20T03:46:36.5066667+00:00

    To shortcut or summarize some of the previous answers that work, do the following:

    1. To fix all of the future files you will download, create a text file that contains the following three lines: Windows Registry Editor Version 5.00
      [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\Attachments]
      "SaveZoneInformation"=dword:00000001
      Save it and rename it ending in .reg. I called mine "Allow-Preview.reg". Double click on it.
    2. To fix the files already on your system, create another text file that contains lines similar to the following: gci -recurse "$Env:userprofile\Documents" | Unblock-File
      gci -recurse "$Env:userprofile\Desktop" | Unblock-File
      Each line would point to a folder where your existing downloaded files are located. Rename your text file ending in .ps1. I called mine "UnblockPreview.ps1". Right click on it and select "Run with Powershell". Note, you may need to disable the execution policy restriction under "System" > "For developers" > "Powershell". Make sure to re-enable it after you're done.

    Also, please note that you must be an administrator on your system to do these things. Do NOT take these lightly, especially number 1 above, because Microsoft disabled preview for a reason. You need to be sure you know that you're not downloading infected files (a difficult thing for sure).

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  5. Christos C 0 Reputation points
    2025-10-20T13:03:06.2833333+00:00

    If you have a 64bit Acrobat, re-download and reinstall it. It should work.
    If you have a 32bit Acrobat, the 64bit Win Explorer can not handle it.

    So, install a 64-bit preview handler. Use a tiny, safe viewer that includes a 64-bit Explorer previewer:

    1. Install SumatraPDF (64-bit).
      • During setup, Go to Options tick “Install PDF previewer for Windows Explorer.”
    2. After install, set Sumatra as default App for .pdf (Settings → Apps → Default apps → pdf = Sumatra) and restart Explorer.
    3. Set Acrobat back as the default app for .pdf (Settings → Apps → Default apps → pdf =Adobe Acrobat).
    4. Open File Explorer → Alt + P to show the Preview Pane → click a PDF.
      • Preview now works (handled by Sumatra’s 64-bit previewer).
      • Double-click still opens in Acrobat.

    This is the cleanest fix when you must keep 32-bit Acrobat.

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