How to Fix PDF Preview Handler Not Working

Published On - August 18, 2025

Emily Harris
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Are you trying to preview a PDF file directly from Windows File Explorer, Outlook, or another application, but the preview pane shows nothing or throws an error? This is a common issue for many Windows users, especially after software updates or configuration changes. The good news is that there are several proven methods to fix the PDF Preview Handler when it’s not working properly.

In this guide, we’ll explore step-by-step solutions to restore your PDF preview functionality. Whether you’re using Adobe Reader, Acrobat, or a different PDF viewer, these tips can help get things back on track.

What is the PDF Preview Handler?

The PDF Preview Handler is a Windows feature integrated into File Explorer and Outlook that allows you to preview PDF documents without opening them. It relies on a registered preview handler component provided by applications like Adobe Acrobat Reader. When this feature stops working, it can be frustrating and interrupt your workflow.

Common Symptoms of Preview Handler Issues

  • Preview pane displays a grey screen instead of the PDF content
  • You see an error like “This file can’t be previewed because of an error with the following previewer: PDF Preview Handler”
  • The preview pane remains completely blank
  • Outlook won’t show PDF attachments correctly in preview

Solutions to Fix PDF Preview Handler Not Working

1. Set Adobe Reader as your Default PDF Viewer

Sometimes, multiple PDF readers installed on your machine can conflict with each other. The Adobe Reader preview handler is only active if Adobe Reader is set as the default PDF application.

  1. Go to Settings > Apps > Default apps
  2. Select Choose default apps by file type
  3. Find .pdf in the list and set Adobe Reader as default

2. Re-Register the Preview Handler DLL

Corrupt or unregistered DLLs can prevent the preview handler from functioning. Here’s how to re-register the DLL associated with the PDF preview:

  1. Open Command Prompt as an administrator
  2. Run the following command:
    regsvr32 "C:\Program Files (x86)\Adobe\Acrobat Reader DC\Reader\pdfprevhndlr.dll"

Make sure the path matches where Adobe Reader is installed on your PC.

3. Repair Adobe Reader or Acrobat Installation

If the installation is corrupted, preview functionality may break. You can repair it as follows:

  1. Open Adobe Reader
  2. Navigate to Help > Repair Installation

Once completed, restart your computer and test the preview again.

4. Tweak the Windows Registry

Warning: Editing the registry incorrectly can cause system issues. Proceed with caution and back up your registry before making changes.

If you’re using a 64-bit version of Windows, older versions of Adobe Reader don’t register their preview handler for 64-bit systems properly. You can fix this by modifying the registry:

  1. Press Win + R, type regedit, and press Enter
  2. Navigate to:
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Classes\CLSID\
{DC6EFB56-9CFA-464D-8880-44885D7DC193}
  1. Double-click on the AppID string. Make sure its value is:
    {534A1E02-D58F-44f0-B58B-36CBED287C7C}

After editing, close the registry and restart your PC.

5. Use a Third-Party PDF Preview Tool

If you’re still facing issues, you might want to consider a third-party solution like PDF-XChange Viewer or SumatraPDF. These lightweight tools often include their own preview handlers and can be configured as default for .pdf files.

Bonus Tip: Clear Your Temp Files

Sometimes temporary files can interfere with preview functionality. You can use Disk Cleanup to clear them:

  1. Type Disk Cleanup in the Start menu and open the app
  2. Select your system drive, then check Temporary files and click OK

Conclusion

When your PDF preview handler stops working, it can disrupt your productivity, especially if you rely heavily on document browsing or email attachments. Fortunately, with the methods outlined above—from simple settings changes to advanced registry tweaks—you can often resolve the issue quickly.

If all else fails, consider updating to the latest version of your viewer or checking for Windows updates, which can often fix compatibility glitches. With just a little troubleshooting, you’ll be back to your previewing routine in no time!