VSTO COM Add-ins for Microsoft Excel installed via Windows store RRS feed

  • Question

  • Hi all,

    Recently I've faced one issue when our COM Add-in does not get installed for some clients who use Excel installed via Windows Store.

    We distribute add-in by setup file, built with Installshield 2013. During installation we write necessary registry entries under 'HKCU\Software\Microsoft\Office\Excel\Addins\AddinName' key.

    If I understood correctly, all changes to HKCU registry are copied to a private per-user location under "C:\Program Files\WindowsApps\package_name" during setup process, same as any files installed under AppData. Excel then uses those copied files/registry entries to load add-in.

    But, as stated earlier, some users reported that Excel simply doesn't 'see' our add-in. Are there any known issues that prevent add-ins from getting loaded or registry entries getting copied to private location? Unfortunately I was unable to reproduce this issue so far and I have no access to client's machines to investigate it more thoroughly.

    Would be grateful for any help/thoughts on the issue.


    Wednesday, November 28, 2018 2:40 PM

All replies

  • Hi Eugene,

    >> But, as stated earlier, some users reported that Excel simply doesn't 'see' our add-in. Are there any known issues that prevent add-ins from getting loaded or registry entries getting copied to private location? 

    Perhaps, you can check for anyone in the UK - The registry entry "LoadBehavior" must be spelled exactly as it appears here.

    For more information, please review the following link:

    Setup Exe File created with InstallShield does not install successfully

    Also other related links for your reference:

    Deploying your Office solutions

    Install and Use Excel Add-ins

    Hopefully it helps you.

    Best Regards,


    MSDN Community Support Please remember to click "Mark as Answer" the responses that resolved your issue, and to click "Unmark as Answer" if not. This can be beneficial to other community members reading this thread.

    Thursday, November 29, 2018 8:33 AM
  • Hi Yuki,

    We write "LoadBehavior" entry during setup process automatically, so spelling is not an issue. Thank you for the links you provided, they are helpful. Unfortunately, the issue persists.

    Do you know where I could learn more about how Windows 10 treats 'write' operations to HKCU registry hive and <user>/AppData folder? In what situations copying of written values to the per-user 'private' location is triggered? Currently most of my knowledge on the topic derived from this resource.

    Friday, November 30, 2018 9:28 AM
  • Eugene,

    The Windows Store edition of Office does not support COM (VSTO) add-ins because, going forward, Microsoft wants developers to build newer "Office add-ins" using the Office.js API instead of more established VSTO add-ins.  The problem is that Office.js is underdeveloped and abysmally incomplete compared to .NET Framework and the Office PIAs / object model used to build VSTO add-ins.

    Therefore, sophisticated VSTO add-ins used extensively in enterprise environments cannot simply be rewritten as "Office add-ins" that support only basic functionality. Enterprise and professional Office users must continue to uninstall the severely handicapped Windows Store edition of Office that now ships with many new PCs and install the fully functional click-to-run edition that supports sophisticated add-ins. Unfortunately, Microsoft has made it difficult to determine whether you have installed the click-to-run or Windows Store edition of Office (perhaps to make the transition to Office.js appear more seamless than it actually is), and not much easier to find the click-to-run download in your O365 account.

    Transitioning from VSTO to Office.js is good, in theory, but Microsoft botched the transition by not providing developers the Microsoft tools (Office.js) they need to help make the transition successful.  Consequently, customers that rely on functionality that only advanced VSTO add-ins can provide (which is most enterprises) are having to ditch the Windows Store edition of Office.

    This isn't the first time that Microsoft introduced major changes in Office that demonstrated unconscionable disregard for their enterprise customers.  Remember Office 2007?

    • Edited by yes98785 Saturday, February 23, 2019 11:26 AM
    • Proposed as answer by Ankur7 Friday, July 26, 2019 10:15 AM
    Thursday, December 20, 2018 12:45 PM