An error message keeps popping up when I open Visual Studio 2010, telling me that the "class designer package did not load correctly".

After searching the web a bit, it seems this can be caused by a misbehaving Add-In. Indeed, I just installed an Add-In (GitExtensions). I've since disabled and removed that add-in, but the error persists. How can I fix this?

1 Answer 1


Ah, it turns out that I had successfully removed the add-in, which made new Visual Studio instances happy, but my actual solution file was still causing this error when opened.

In order to get my solution to open without causing the error I had to delete the (hidden) .suo file that resided alongside the .sln file (note this will clear all bookmarks, breakpoints, last-open-files, etc.). Apparently the .suo was referencing the removed add-in somewhere!

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