XF 2.0 Still can't upgrade - this time it's a non existent addon

[Mr Lucky]

When I try to upgrade to beta version 2 I get this:

Conflicts with the following third-party add-ons have been detected:
Conversation Improvements by Xon
Upgrading XenForo is not possible until these conflicts have been resolved. Resolving these errors will generally require you to restore the XenForo files from your previous version and uninstall the conflicting add-on or upgrade it to a non-conflicting version. The add-on author may have more specific advice as to the steps you can take.

However I had already uninstalled that addon (and its files)

So what do I do now?

 

[StarArmy]

I had an idea for a workaround:

1. Create a second "clean" 1.5 installation on your server (XF allows two installs per license if they're on the same server and one is for testing)
2. Import your main 1.5 forum into the "clean" (no add-ons) secondary forum
3. Upgrade the "clean" forum instead of the one with add-ons
4. Delete the old 1.5 and replace it with your new 2.0