You are doing a major update, why not just spend 10-20 seconds to read the update instruction before doing such a large update?

It's clearly mentioned in the release summary, in the update changelog and in the update instruction that old addons are not compatible with wpForo v2, you should update addons to 3.0.x verion before updating wpForo to 2.0.x.

Now, just update your addon to the latest 3.0.0 version and all will be ok.