Attachments can’t be downloaded or previewed from Outlook

Question/Issue

I am unable to preview or download attachments in Outlook.

• Attachments fail to download, with errors such as “Error downloading the file content”
• Preview pane remains blank or shows “This file cannot be previewed”
• Some attachments (e.g., PDFs) show as blocked or unavailable

Environment

• Outlook

Cause

The issue can stem from several root causes:

• Incorrect Trust Center preview settings or missing preview handlers
• Mismatched or missing previewers for file types like PDF, Word, Excel
• Conflicts from third-party tools (e.g., PowerToys PDF preview)
• Incorrect mailbox time zone settings in Outlook on the Web
• Outdated Outlook or Exchange server versions
• Browser cache, extensions, or compatibility issues when using OWA
• Corrupted Outlook profile or disabled services (e.g., Windows Firewall)

Resolution

1. Verify Attachment Preview Settings

• In Outlook for Windows, go to:
  File → Options → Trust Center → Trust Center Settings → Attachment Handling
  • Uncheck “Turn off Attachment Preview”
  • Click Attachment and Document Previewers…, and ensure handlers for PDF, Word, Excel, etc., are enabled
• Restart Outlook and test preview functionality.

2. Disable Conflicting Third-Party Previewers

• If using PowerToys, open it, select File Explorer Add-ons, and disable PDF preview
• Restart Outlook to allow default preview handler to load

3. Match Application and Previewer “Bitness”

• Ensure Outlook and your PDF viewer (e.g., Adobe Reader) are either both 32-bit or both 64-bit
• If mismatched, reinstall the PDF viewer to match Outlook’s architecture

4. Adjust Mailbox Time Zone (OWA)

• In Outlook on the Web, open the affected mailbox, then go to:
  Settings (gear) → General → Language and time
• Set the correct time zone, save, then refresh or reopen Outlook

5. Update Outlook and Exchange Components

• In desktop Outlook:
  File → Office Account → Update Options → Update Now
• For on-premises Exchange: ensure you’re running the latest cumulative updates
• After updating, attempt download/preview again

6. Clear Cache & Test in Another Browser

• For OWA, clear your browser’s cache and cookies, disable extensions (especially privacy/ad blockers), then test again
• If issues persist, try using a different browser or the light version of OWA (add ?layout=light to the URL)

7. Repair Office Installation & Profile

• Navigate to the Windows App list, select Microsoft Office → Change → then choose Quick Repair
• If issues persist, recreate the Outlook profile or consider moving to a new one