Thanks for your reply. It's a rare day when I'm not the first (or one of the first) to apply updates, but because of personal issues that generated a lot of stress, I didn't even get to update anything until late Saturday afternoon. And I still had little time to spend on it, so for a change I didn't read any of the other posts before I started updating.
When I couldn't get to sleep tonight, I fired up my laptop, discovered that another update was available, and installed it. I can confirm that the apparmor issue is gone, and as @Harvey noted, the reboot command now works by itself in the terminal.
I'm going to start updating all the rest of the machines here, until I'm too sleepy to continue, then I'll try going to bed again.
