I had a problem that was pretty much the opposite of UCAPs (above)..
A few years ago, we bought a then state of the art Lexmark A3 colour Laser printer. I was primarily responsible for this (no idea why - while it was flasher than our normal printers, it was just a printer), with another technician helping.
It had a particular problem where the paper would jam in the Duplexer, and multiple engineers from Lexmark failed to fix the problem. There was a particular trick to getting the paper out of the duplexer and resetting it. Me and my colleague both knew the trick.
For the first time in *years*, I went on holiday, going to Vegas. When I got back, my boss was in a foul mood, and shouted at me that this printer he'd spent so much money on was not working (he actually hadn't, we provided support for the printer, but it was bought by another department). It had been out of order for a week. The fix was to push a tiny part of the mechanism back into the right position.
I told him to calm down, and I would look at it. Sure enough, the paper had jammed in the Duplexer. I cleared it, and left the printer clearing the huge backlog of jobs that had built up.
I asked the technician that supported the printer with me why he hadn't fixed it. He said he wasn't aware there was a problem. He worked for a different department, the one who actually owned the printer. My department supported it on condition our users were allowed to use it.
I suspect what had happened is our users tried to use it, failed, then complained to my boss, who didn't really investigate, just shouted at me.
I went to see my boss. I pointed out that there was another technician who could have fixed the problem, but no one bothered to contact him. I also pointed out that the entire department had my mobile number (I had my mobile with me), and in an emergency, they *could* have contacted me, and I would have taken them through the process of fixing it.
He said "but you were on holiday". I answered, asking why no one had contacted the other technician, and pointed out that while I am happy to carry the can if I have failed in some way, I hadn't failed, I wasn't going to take the blame for someone else's failure. He did sort of apologise..