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VSTO Excel Add-in does not load RRS feed

  • Question

  • I have been working on a pair of Excel add-in for over a year.  They were developed using Visual Studio 2017 using VSTO and have run on dozens of user computers under Excel 2010, 2013 and 2016 without a problem.  I've run it on a handful of other computers.

    Recently, I got a new computer (Windows 10 64 bit; MS Office 365) and the add-ins do not load.  (Well, the machine has 2 users.  One user can run add-in A but not B and the second user can run B but not A.)  This is the same environment as another computer where the add-ins both run fine.

    Both add-ins have the required registry keys (under Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\Excel\Addins)

    They do not show as disabled or in the list of add-ins known to Excel at all.

    Environment var VSTO_SUPPRESSDISPLAYALERTS is set to 0 but no information appears on the screen.

    There's nothing in the Event Viewer.

    Fusion logging didn't show any relevant issues.

    I've tried reinstalling the add-ins; repairing Excel.

    What can I do to figure out what's going on here?


    Thursday, June 20, 2019 3:11 AM

All replies

  • I have a very similar issue.  Running VS 2019 and just created a basic Excel VSTO add-in with only the default code for StartUp and Shutdown.  When I place a breakpoint in StartUp, the code does not break after starting debugging.  I am running Windows 10 and Microsoft 365 version of Office (16.0.12730.20144) 32-bit.

    I thought I read that the Microsoft Store version of Microsoft 365 has trouble running VSTO add-ins, but I haven't found a solution.

    Wednesday, May 6, 2020 5:06 PM