Attachment Previews - Outlook 2016 (O365) RRS feed

  • Question

  • I have a user that is running Outlook 2016 (O365) on a Windows 10 machine. There are two issues with attachments.

    1. There does not appear to be a .pdf previewer installed. I checked the Trust Center and there is none listed.
    2. When the user attempts to preview a Office 2016 attachment (Word, Excel, PowerPoint) the preview may or may not work. If it does work, it often locks up Outlook so that you can't even navigate away from the preview. The only way to break free of the issue is to kill the process in Task Manager and reopen Outlook.

    I have searched around the net and found lots of issues related to preview not working in Outlook 2016 but nothing with the same specific issues. I have not found any remedies... I ran both the quick repair and the longer repair which seems to reinstall Office. No luck. 

    Any suggestions?

    Tuesday, November 29, 2016 9:31 PM

All replies

  • Hi,

    Re #1

    Correct. There is no PDF attachment previewer installed in Outlook. You will need to install the Adobe PDF Reader in order to preview PDF attachments in Outlook. If you already have the PDF reader program installed and this issue still happens, please try uninstalling the Adobe Reader and then reinstall the latest version from its official website.

    Re #2

    Is there any application error logged in the Event Viewer when this issue happens?

    Please try cleaning out the Outlook SecureTemp Files Folder which is used to store Outlook attachment cache and then check if this issue continues. The SecureTemp folder location is stored in the OutlookSecureTempFolder registry key in the following registry path:


    For more information about how to clean out the Outlook Secure Temp folder, please refer to the following article:

    Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

    Hope this helps.


    Steve Fan

    Please remember to mark the replies as answers if they helped.

    If you have feedback for TechNet Subscriber Support, contact

    Wednesday, November 30, 2016 7:51 AM
  • Thanks Steve!

    Sorry it has taken me a bit to respond. I wanted to give the user enough time to exercise Outlook to insure the problem was corrected. 

    1. .pdf previews - Adobe DC reader was already installed so I took  your advice and uninstalled and reinstalled.  This seems to have fixed the problem.  Outlook is now able to preview .pdf attachments.  YAY!
    2. MS Office attachments - Unfortunately fix number two above was not as successful. I cleaned out the Outlook SecureTemp folder per your instructions. It seems to have stabilized somewhat but Outlook continues to lock up when you attempt to initiate a preview of Word, Excel or PowerPoint attachments. :(

    Any further suggestions for #2 above would be appreciated.



    Thursday, December 1, 2016 6:21 PM
  • Thank you for the update and good to hear that the first problem has been fixed.

    For the second question, does this issue continue if we try to start Outlook in safe mode and then preview the attachment?

    I noted that the issue happens randomly, did you notice ant trigger of this issue? Such as whether this issue happens when previewing large documents?

    In addition, we may also try to export the attachment previewer related registry keys from a working computer and then import it to the problematic one to see the result. The previewer related registry entries are stored in the following registry path:

    1) For a Click-to-Run installation of any bitness of Outlook and Windows, locate and then select the following registry key:


    2) For an MSI installation of 32-bit Outlook on 64-bit Windows, locate and then select the following registry key:


    3) For an MSI installation of 32-bit Outlook on 32-bit Windows or 64-bit Outlook on 64-bit Windows, locate and then select the following registry key:


    Important Serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it.

    Please let me know the result.


    Steve Fan

    Please remember to mark the replies as answers if they helped.

    If you have feedback for TechNet Subscriber Support, contact

    Tuesday, December 6, 2016 8:13 AM
  • Thanks again Steve...

    First to clarify; Previewing files in Outlook does work but the application randomly freezes and requires the user to close Outlook via Task Manager.

    1. I was unable to launch Outlook while in Safe Mode but made progress on your other suggestions.
    2. There seems to be no discernable pattern regarding size of the attachment or file format. I have noticed that I am more likely able to cause a freeze if I quickly navigate from attachment to attachment. One might think that could be caused by an underpowered machine. The machine in question is a Dell Latitude e7440 with and i7 and 16 GB of RAM. When asked, the user indicates that she does not move from attachment to attachment quickly.
    3. I successfully exported the registry settings from my machine (which is working fine) to the users machine. The good news is Outlook still works as does Attachments previews. The jury is still out whether it fixed the problem... I previewed lots of attachments and moved from one email to the next and continued to exercise the function.  All seemed to work fine.

    I will monitor the situation for the next few days and report back.

    Thanks so much for all your help.  This has been very useful!





    Tuesday, December 6, 2016 8:24 PM
  • Hello,

    Any update on this issue? If you need further assistance on this issue, please don't hesitate to post back.

    By the way, if you find the reply is helpful, would you mind to mark the reply as answer, so it will be easy for other community members to find the useful one?

    Thank you for your understanding.


    Steve Fan

    Please remember to mark the replies as answers if they helped.

    If you have feedback for TechNet Subscriber Support, contact

    Wednesday, December 14, 2016 8:03 AM
  • Steve:

    Many thanks for your follow-up. My user was away and focused on other tasks over the last few days so she was not exercising the issue. I had her play with it this morning and unfortunately the problem persists. Again, there does not appear to be a relationship to size or type of the files she is previewing.

    Do you have any miracle cures up your sleeve?





    Wednesday, December 14, 2016 7:33 PM