Packages missing in Ubuntu that worked in Debian
I've set up lots of servers that run the Debian flavour of Linux. It's light-weight (works on little RAM, if installed in a minmal configuration) and extremely stable.
But for a particular purpose I recently needed to run a server using Ubuntu 18.04 LTS.
I hit a newbie gotcha that had me stumped for a while, but once I'd solve it, it was really simple.