Removed Oracle Java (version 8) packages, with intention to replace it with OpenJDK (11).
OpenJDK is installed, now JNLP won’t work. JOSM’s JAR file just works, but I’ll definitely miss any auto-update feature.
Tried and tested several other guides… nope! JNLP would still not work.
Finally, purge everything Java and… attempt to reinstall someday.
Discussion
Comment from Sanderd17 on 14 July 2020 at 10:45
Oracle removed webstart from newer versions.
So JNLP is a dead technology. Even on Oracle Java.
Comment from AkuAnakTimur on 15 July 2020 at 13:21
@Sanderd17
Uh oh! Looks like I’ve got to stick with the JARs from now on.