If you’ve ever worked on a VSTO addin, you may know how frustrating it can be to try debugging problems with them, especially problems of the “my addin isn’t being loaded” variety.
There is a way to get a little more information on the process, however.
Just set the environment variable VSTO_SUPRESSDISPLAYALERTS to “0″, and then restart the Office app of you choice.
Now, instead of just quietly failing, the VSTO loader should be a little more verbose about what’s happening.
In my particular case, it didn’t help all that much, but I could definitely see it helping in many cases.
Microsoft also has a KB article about it, but you’d almost never find it unless you knew what your were looking for up front.