Hello,
Ever since I updated to Kubuntu 26.04 from 25.10, I have experienced several abnormal behaviours with JOSM. The most severe of these behaviours is that plugins seem to completely no longer work. As you can see in the second image, I have many, many plugins installed into JOSM. However, I notice that if JOSM is not used for about 5 minutes, then the next startup, JOSM will totally ignore the plugins and not load them at all. We can see in the second picture that JOSM clearly sees these files, but for whatever reason chooses not to load them. When I go to the plugins settings page, I see that JOSM claims that nothing is installed. I then have to manually install all of the plugins again. The next restart, it does work, but subsequent restarts fail again.
I have been unable to find any settings relating to this, but I am not skilled in configuring JOSM in an advanced manner. I have tried changing my icedtea javaws java version as if that would make a difference, but this effect occurs on java 11, 21, and 25 (the JREs that I have installed).
I cannot find any information pertaining to this topic at all, maybe partially because search engines assume I am asking HOW I can delete all plugins/ignore all plugins…