hey there,

First we updated easyblog to its latest version and later we installed easyblog in fresh Joomla 3.
Later, we moved all easyblog tables from old site to new one.

It seems like your instruction is not follow correctly as what I suggested you in previous post.

By right, you should move all the easyblog table from old site to new site first.
After that, you only install latest version of Easyblog in your new site.

By the way, regarding with your main issue, I've checked in your existing post from backend, it seems like some of the blog post didn't have assign any category and author from the blog post, you can refer on my attached screenshot below.

To fix this, you have to double check all the existing post is it assigned the correct category and author, so that when you perform any action like publish/unpublish/delete/trash, the system will not throw out the error.