Hi, I have the same issue, this is what I've found so far:
- after plugging in the Arduino and starting the IDE, the status line reports the correct settings (board type and serial device selected in a previous session) - just klicking on the 'Tools' menu throws the error message: java.lang.NullPointerException thrown while loading gnu.io.RXTXCommDriver - the user running the Arduino IDE is in the dialout group, I tried if chmod 666 on the serial device would help but it didn't - tried to send a sketch to the Arduino, this produced the following two lines repeatedly: java.lang.NullPointerException thrown while loading gnu.io.RXTXCommDriver PORTS {} / {} => {} then followed by: processing.app.debug.RunnerException: Couldn’t find a Leonardo on the selected port. Check that you have the correct port selected. If it is correct, try pressing the board's reset button after initiating the upload. at processing.app.debug.AvrdudeUploader.uploadViaBootloader(AvrdudeUploader.java:154) at processing.app.debug.AvrdudeUploader.uploadUsingPreferences(AvrdudeUploader.java:67) at processing.app.Sketch.upload(Sketch.java:1671) at processing.app.Sketch.exportApplet(Sketch.java:1627) at processing.app.Sketch.exportApplet(Sketch.java:1599) at processing.app.Editor$DefaultExportHandler.run(Editor.java:2380) at java.base/java.lang.Thread.run(Thread.java:844) -- System Information: