Thanks igorp, good to know. I was referring to:
https://docs.armbian.com/Developer-Guide_Build-Preparation/
The only supported compilation environment is Ubuntu Bionic 18.04 x64 ( no other releases are supported ! It has to be exactly 18.04 otherwise default compiler versions might not match so if you’re on an older Ubuntu release upgrade to 18.04 now, if you use a newer Ubuntu version start with 18.04 from scratch),
Which at least means that if i encounter any problem compiling anything armbian and want to ask a question, the likely answer will be “use ubuntu 18.04 first, then come back” ;-(