There is probably a compatibility issue in the FreePHP plugin (maybe because a new version of PHP) which you might be able to fix (I think you're missing the very first error in the log you show).

Anyways, we are going to integrate this feature into b2evolution as a core widget.

That's super helpful to be an integrated part, but doesn't exactly help at this point. ^_^; I realized something earlier, too. When I first upgraded, I wasn't getting that error. I was still using the old msql_query, and I was given the error that it's be deprecated and will soon be removed. So I changed to msqli, and while it works just fine on the page, that's when I started getting the errors. Which honestly makes no sense, since I get it on blogs that don't use freephp. I attached screeshots of the errors I get. Like I said, it does seem to post just fine, these errors are only appearing on the back end. The first one is what happens when I publish or save a post, the second one is the error I get on most of the backend pages. I also get the first one when I remove an attached file, in the little file display box at the bottom.

Do we agree that if you remove the "freephp" plugin, the errors go away?

If I turn it off site-wide, then I don't get it on the post pages. However, when I went back to the system plug-in page, it's still there on top. I have to delete it off the server to not get that error anywhere.

Yes, you should delete it from your /plugins/ folder.

What code are you trying to put in there?

Try putting that code directly into the skin files for now.

It's a code for pulling most recent graphics from a separate database that's on the sidebar. That's one of the things I'm hoping to migrate to b2evo, but that's going to take me a long while to do so, so having it pull from that separate database is necessary for now.

You can probably locate the "Sidebar" and/or "Sidebar 2" containers in the skin you're using and add your code above or below one of them.