Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

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?

share|improve this question

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!

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.