PREVIEWER IN NOT INSTALLED ON OUTLOOK

To restore document preview in classic Outlook, use these steps depending on what is being previewed.

1. Verify Outlook and Office apps are installed and matched

• The attachment previewer in classic Outlook requires the same version of Word/Excel/PowerPoint as Outlook.
• If Outlook is Microsoft 365 classic, ensure Microsoft 365 Apps (Word, Excel, PowerPoint) are installed from the same subscription.
• If different versions are mixed, uninstall the older/other Office version and reinstall Microsoft 365 Apps so Outlook and Office apps match.

2. Turn on attachment preview in Outlook Trust Center

1. In Outlook, select File > Options.
2. Select Trust Center > Trust Center Settings.
3. Select Attachment Handling.
4. Make sure Turn off Attachment Preview is not checked.
5. Select Attachment and Document Previewers and ensure the previewers (Word, Excel, PowerPoint, etc.) are checked.
6. Select OK to save.

3. Preview attachments correctly

• In the Reading Pane, click the attachment under the Subject line, or right‑click the attachment and select Preview.
• Attachments embedded in the message body cannot be previewed; those must be opened directly.

4. Fix PDF preview specifically (if PDFs show “no previewer installed”)

• Ensure a PDF previewer is installed and aligned with Outlook:
  • If using Adobe Acrobat Reader, its bitness (32‑bit or 64‑bit) must match Outlook.
  • In Outlook, go to File > Office Account > About Outlook to see 32‑bit or 64‑bit.
  • In Adobe Reader, go to Help > About Adobe Acrobat Reader to check bitness.
  • If they differ, uninstall Adobe Reader and reinstall the version that matches Outlook’s bitness from Adobe’s “other versions” page.
• If Microsoft PowerToys is installed, open PowerToys, go to File Explorer Add-ons, and disable Enable PDF (.pdf) preview so Outlook can use the correct previewer.

5. Ensure Windows Firewall service is running (for Office file preview errors) If the error appears when previewing Word/Excel/PowerPoint attachments (not PDFs) on Windows 10/8.1/8:

1. Press Windows key + R, type services.msc, select OK.
2. Find Windows Firewall (or Windows Defender Firewall), right‑click and select Properties.
3. Set Startup type to Automatic, select OK.
4. Right‑click Windows Firewall and select Start.

After these steps, restart Outlook and test previewing a Word, Excel, or PDF attachment from the Reading Pane.

References:

• Outlook PDF preview error: This file cannot be previewed because there is no previewer installed for it
• Can't preview Office documents in Outlook if Windows Firewall Service is disabled
• Open, save, and edit attachments received in Outlook
• Fixes or workarounds for recent issues in classic Outlook for Windows