A developer posted a couple of days ago in the MSDN forum about Visual Studio Extensibility that loading his add-in caused and exception with error number <Unknown Error> (8013141A). Of course, searching with Google doesn’t always offer much information about these bizarre errors, nor the tools of the Windows SDK for which this error is, well, unknown too.

Since the section of my article about troubleshooting crashes in add-ins didn’t help much, I have enhanced it with further and more detailed explanations, and a mention to this error:

HOWTO: Troubleshooting Visual Studio and Office add-ins
http://www.mztools.com/articles/2007/MZ2007009.aspx