Outlook add-in disappears but does not appear to be disabled RRS feed

  • Question

  • I am having weird behavior with a VSTO Outlook add-in I am developing.  At first, we had the 'slow add-in' warnings, but those went away after we changed the installer to use a LoadBehavior of 16 and added ourselves to the 'DoNotDisableAddinList' reg key.  But, now some users are saying the add-in just disappears from the toolbar after an outlook startup.

    When this occurs, there are no slow-add warnings and it's not in the slow add-in dialog.  If I go to File > Options > Add-ins > Go, i see that it's enabled.  yet, the button is gone from the toolbar.  There are no Windows logs to indicate why it failed to load.

    If we disable and enable the Add-in checkbox, it will sometimes re-appear.

    Another oddity I've noticed is that after an install, that same checkbox is actually unchecked, as if it were disabled, but it does show up in the toolbar and it works great.  In other words, the Add-in checkbox is reversed of what it should be doing.  i am not 100% sure that this checkbox oddity is related to my disappearing add-in button, but I think it's likely.  

    Thursday, May 16, 2019 6:15 PM

All replies

  • In Outlook's options, check the "Show add-in user interface errors" box.  If Outlook displays a message box indicating an error that may give you a clue.
    Thursday, May 16, 2019 8:52 PM