Custom Microsoft Project Add-In disappears randomly

Question

the AddIn (*.vsto) for Microsoft Project 2010 Client I developed for a customer installs (via the MS Setup Wizard) and runs perfectly fine most of the time. However sometimes it simply disappears from the tool-bar after a restart of MS Project. Even though not beeing shown in MS Project anymore the AddIn is still listed in Windows Software Manager and has to be deleted there before it can be reinstalled. The customer does not recieve any error message at anytime. Therefore it is very difficult to find the cause of the problem. Did anybody have the same problems or knows how to get rid of them?

Thank you in advance.

Answer 1

Check the Disabled Items list.

Whenever an office application crashes and an add-in was deemed to be at fault, it is silently added to the Disabled Items list. Click the Office button, Project Options, Add-Ins, select Disabled Items from the Manage list and click Go. If you see your add-in, select it and click Enable.

Here is an MSDN page that discusses the issue within the context of debugging your application, but the steps to enable are the same for the end-user.

Microsoft Office applications can disable add-ins that behave unexpectedly. If an application does not load your add-in when you try to debug it, the application might have hard disabled or soft disabled your add-in.