Microsoft documents one reason a PDF attachment fails to preview in classic Outlook for Windows. Outlook shows a message about a missing previewer for the file. Microsoft names two causes, an Adobe Acrobat Reader bitness mismatch and the PowerToys PDF preview setting. Matching the Reader bitness to Outlook or switching off the PowerToys setting is the Microsoft fix. Opening a PDF from Outlook falls outside this article.
You select a PDF attachment and the reading pane shows an error instead of the file. Outlook says that it cannot preview the file.
Facts follow the Microsoft Support known issue Outlook PDF preview error. Microsoft marks it as a temporary fix and lists Outlook for Microsoft 365 on the desktop. Microsoft last updated the page on March 18, 2022.
What is the PDF Preview Error?
Previewing a PDF attachment from an email fails in classic Outlook for Windows. Outlook states that it cannot preview the file because no previewer is installed for it.
Preview is the only failure here. Microsoft does not describe a PDF that fails to open after you double-click it.
What are the Two Causes?
- Bitness mismatch. Adobe Acrobat Reader and Outlook are installed in different bitness, one 32-bit and the other 64-bit.
- PowerToys override. Microsoft PowerToys is installed and its PDF preview setting overrides the default PDF preview.
How to Fix the Bitness Mismatch?
- Open Outlook and select File, Account and then About Outlook. Outlook shows its bitness in bold at the top.
- Open Adobe Acrobat Reader and open the About Adobe Acrobat Reader entry in its Help menu. Its bitness appears in bold at the top.
- Go to the PowerToys steps below when both match. When they differ, uninstall the current Acrobat Reader.
- Open the Adobe page named Acrobat Reader DC installation for all versions and download the build that matches Outlook. Choose 64-bit when Outlook is 64-bit.
- Start the installer and follow the prompts.
How to Fix the PowerToys Override?
- Search for PowerToys in the Windows Start menu and open it.
- Select the File Explorer add-on.
- Switch off the PDF (.pdf) preview setting.
What does Microsoft Not Say?
- Whether the same fix applies to older Outlook versions. Only Outlook for Microsoft 365 appears in the article.
- Any fix for PDFs that fail to open after you double-click them.
- Permanent product fix. Microsoft lists the article as a temporary fix.
Related reading: how to fix Outlook attachments that will not open and how to fix an Outlook attachment download error.
Frequently Asked Questions
Why does Outlook Say No Previewer is Installed?
Microsoft names two causes. Acrobat Reader bitness can differ from Outlook bitness. Alternatively the PowerToys setting overrides the default preview.
How do I Check the Outlook Bitness?
Select File, Account and About Outlook. Outlook shows the bitness in bold at the top of the dialog.
Does Reinstalling Acrobat Reader Fix It?
Only when the bitness differs from Outlook. Microsoft advises downloading the Reader build that matches Outlook.
Does PowerToys Cause the PDF Preview Error?
Yes in one documented case. Microsoft states that a File Explorer add-on setting in PowerToys overrides the default preview.
Does This Fix a PDF That Fails to Open?
Microsoft does not say. It describes the preview error only.
Key Takeaways
- Outlook reports a missing previewer for the PDF.
- Microsoft names an Acrobat Reader bitness mismatch as the first cause.
- PowerToys is the second cause through its PDF preview setting.
- Matching the Reader build to Outlook fixes the first cause.
- Microsoft lists Outlook for Microsoft 365 and marks the fix as temporary.
Sources and References
Facts follow Microsoft Support.
- Outlook PDF preview error (Microsoft Support known issue) support.microsoft.com