Setup the Environment

Java 8 is necessary:

In case of Ubuntu 18.10+ you have to add ubuntu bionic repository first:

sudo apt-add-repository "deb http://de.archive.ubuntu.com/ubuntu/ bionic universe"

JavaFX 8 is necessary and not included in openjdk package. And you have to specify the older javafx 8 version explicit:

Next install JavaFX 8 and downgrade eventually newer versions:

sudo apt install openjfx=8u161-b12-1ubuntu2 libopenjfx-java=8u161-b12-1ubuntu2 libopenjfx-jni=8u161-b12-1ubuntu2

IntelliJ sbt project “api” import:

Watch “project” module is sources root. In my case IntelliJ definite the server module to it. Here can help to delete all /target folder in api project, detach the sbt project in “sbt view” and import sbt project again (maybe first restart IntelliJ and follow the suggestion to import).