i'm installing in ubuntu 20.04.
the regular installation detailed on idempiere's website did not work
https://wiki.idempiere.org/en/Installing_iDempiere
i followed the procedure, but got an error with java (a javax.xml error). after a bit of digging i read that apparently, openjdk 11 (which is recommended on the installation) is uncompatible with java.xml. I'm not sure if this is the culprit, but i believe that this installation is broken.
so i followed a different installation procedure using the debian build, also on idempiere's website and it worked like a charm.
https://wiki.idempiere.org/en/Install_Prerequisites