Ever since I upgraded to Outlook 2016 my attachment PDF Previewer has stopped working with the message

This file cannot be previewed because of an error with the following previewer:

PDF Preview Handler

To open this file in its own program, double-click it.

screenshot of the error message

I tried these fixes without any luck:

8 Answers 8


For my user, they had not opened Adobe Reader yet. Opening it and agreeing to all the licensing resolved the issue.


After trying all of the above, a restart did the trick. Doh!


Open the registry editor, search for "OutlookSecureTempFolder" copy the Value data and paste it on the explorer url bar + Enter, and highlight and delete all items in this folder


Disabling Internet Auto Detect did the trick for me.
For example, on...

  • Windows 10 64 bits
  • Adobe Acrobat Pro or Adobe Reader DC
  • Outlook 2016 (32bits)

...do the following:

Open Adobe Reader -> Go to Edit menu -> Preferences -> Click Internet -> then Internet Settings -> Click LAN Settings -> Uncheck the box -> “Automatically detect settings" -> Click OK button and close Adobe

  • Of course, if that fixes it, you likely have a broken proxy, a broken DNS, or a broken network stack. Jul 4, 2020 at 19:33
  • Warning that this changes global settings for your computer's network connection, its not specific to Adobe.
    – Jacktose
    May 7, 2021 at 21:55

Check Adobe Reader compatibility mode; if you use Office 2016 and an OS like Windows Server 2016 or Windows 10, then select "Run this program in compatibility mode for - Windows 8".



Open Adobe Reader X or XI etc ... on Menu > Edit > Preferences > General > Click Select "Default PDF Handler" at the bottom of the screen > Click Apply on the popup > OK.

Good luck!


In my case, I was using Adobe Reader, but the install was new and I hadn't yet opened Reader directly to accept the EULA. Once I had done that, the preview in Outlook worked.

  • @fixer1234 - I believe the user is suggesting that due to the EULA not being accepted the PDF preview was not working within Outlook
    – Ramhound
    May 29, 2019 at 14:04

I had the same problem while using Acrobat Pro and Outlook 365. .pdf handler issue. My solution, close outlook, download Adobe Reader DC, then re-do a file association with Acrobat Pro to open the .pdf. File handler icon changed to Reader and opens in Acrobat Pro.

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