For some oddball reason, since installing I have had no reason to print from an Ubuntu MATE 16.04 system. Until the other day, just before departing for a long weekend. All I got from Ubuntu was random characters. I rebooted into Slackware to print.
Upon returning from the trip I tried again. And again. And again. Never in the 14 years I have been using Linux based systems have I had a problem printing to my HP LaserJet 4200.
In the end I had no clue why Ubuntu utterly failed at printing. There was much weeping and gnashing of teeth. Lots of anger and wasted paper.
I deleted all CUPS config and cache files. I then copied the same files from Slackware.
Instantly I could print without event.
I can’t print to an HP LaserJet? Inexcusable. Completely.