Enabling / Fixing PDF Preview for Outlook on Windows 10

In this post, I am detailing the steps I did to fix the PDF Preview on Outlook running on Windows 10, since some customers that are using Windows 10 for Azure Virtual Desktop (AVD) asked me a guidance for this.

If you are running Windows 11, you can skip this post, since it is already working by design. At least, it was supposed to.

Just as a spoiler, I made it work by setting Microsoft Edge PDF Preview Handler on Microsoft Outlook.

This file cannot be previewed because there is no previewer installed for it

That was the message error that I was getting when I tried to preview a PDF file for Outlook running on Windows 10 of my Azure Virtual Desktop environment.

Steps to Fix it

The steps to fix it are really simple, but it took me a lot of time to figure out the registry keys that must be changed. I used the Process Monitor to find the values that were missing. But don't worry, I am omitting the PROCMON analysis and going straight to the point. 🙂

Follows the keys that you need to add on registry. You can copy and save it in a .reg file (something like pdfpreview.reg) and run it to add those settings to registry. You will need admin privileges for it. 

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.pdf]
"Content Type"="application/pdf"

[HKEY_CLASSES_ROOT\.pdf\OpenWithProgids]
"AppXd4nrz8ff68srnhf9t5a8sbjyar1cr723"=hex(0):
"AppXhaf982pj5x803bbs896zjjytm0naym8x"=hex:
"MSEdgePDF"=""

[HKEY_CLASSES_ROOT\.pdf\PersistentHandler]
@="{1AA9BF05-9A97-48c1-BA28-D9DCE795E93C}"

[HKEY_CLASSES_ROOT\.pdf\ShellEx]

[HKEY_CLASSES_ROOT\.pdf\ShellEx\{8895b1c6-b41f-4c1c-a562-0d564250836f}]
@="{3A84F9C2-6164-485C-A7D9-4B27F8AC009E}"

[HKEY_CLASSES_ROOT\CLSID\{3A84F9C2-6164-485C-A7D9-4B27F8AC009E}]
@="PDF Preview Handler"
"DisplayName"="PDF Preview Handler"
"AppID"="{6d2b5079-2f0b-48dd-ab7f-97cec514d30b}"
"EnablePreviewHandler"=dword:00000001

[HKEY_CLASSES_ROOT\CLSID\{3A84F9C2-6164-485C-A7D9-4B27F8AC009E}\InProcServer32]
@="C:\\Program Files (x86)\\Microsoft\\Edge\\Application\\104.0.1293.54\\PdfPreview\\PdfPreviewHandler.dll"
"ThreadingModel"="Apartment"

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\PreviewHandlers]
"{3A84F9C2-6164-485C-A7D9-4B27F8AC009E}"="Microsoft PDF Previewer"

Notice that you have to set the path for [HKEY_CLASSES_ROOT\CLSID{3A84F9C2-6164-485C-A7D9-4B27F8AC009E}\InProcServer32] with the version of the Microsoft Edge that is installed on your environment.

As I was using a clean Windows 10 image, I found out that I also need to install the Microsoft Edge WebView2 runtime. But probably you already have it installed on your environment.

Finally, after adding those keys to registry and having installed WebView2 runtime, I successfully enabled PDF Preview for Outlook.

I hope that those steps can help you too.