Illegal reflective access by processing.app.linux.GTKLookAndFeelFixer

[mMerlin]

Environment:

• 4.18.16-300.fc29.x86_64
• Arduino 1.8.5

This is a fresh load from scratch of Fedora 29 from Fedora-Workstation-Live-x86_64-29-1.2.iso.

sudo dnf upgrade
flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
flatpak install flathub cc.arduino.arduinoide
sudo usermod -a -G dialout «…»

reboot

$ flatpak run cc.arduino.arduinoide 
Picked up JAVA_TOOL_OPTIONS: 
Gtk-Message: Failed to load module "pk-gtk-module"
Gtk-Message: Failed to load module "canberra-gtk-module"
Gtk-Message: Failed to load module "pk-gtk-module"
Gtk-Message: Failed to load module "canberra-gtk-module"
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by processing.app.linux.GTKLookAndFeelFixer (file:/app/Arduino/lib/arduino-core.jar) to field com.sun.java.swing.plaf.gtk.GTKLookAndFeel.styleFactory
WARNING: Please consider reporting this to the maintainers of processing.app.linux.GTKLookAndFeelFixer
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

The app still runs correctly, as far as I can tell. Currently only a warning, but the messages say it will be denied in a future release. Of flatpak I assume.

[per1234]

Please always use the official Arduino IDE downloaded from https://www.arduino.cc/en/Main/Software. The flatpak installation is giving you an Arduino IDE version that's a year out of date. It may also have been modified in unknown ways, which could cause bugs that don't occur with the official IDE. We can't be responsible for troubleshooting bugs caused by 3rd party modifications.

Before reporting a bug, please always test with the hourly build of the Arduino IDE:
https://www.arduino.cc/en/Main/Software#hourly
to make sure that the problem has not already been fixed. It's not helpful to report issues that only occur with outdated IDE versions.

I'm going to go ahead and close this, but if you find the issue still occurs with the hourly build then please comment here and I'll re-open.

[mMerlin]

I missed that the flatpak was not part of the official software. Repeating the issue information for flatpak maintainers flathub/cc.arduino.arduinoide#5

[A6GibKm]

I updated the flatpak app to use the latest version (1.8.13) and the issue persists, the only 'unknown' modification is that we are using java from opejdk11. It seems this is a java issue and it might be interesting to have it in mind.

[jackaranda7691]

[jackaranda7691]

I'm new to this and first time try at being an Arduino user. I don't understand much of the error messages but your thread seems relevant. Help! ??

[jackaranda7691]

processing.app.linux.GTKLookAndFeelFixer

I noted that permissions may be a problem. However the permission Checker box never appeared and I don't know how to add myself to dialout, (which currently doesn't show me, just ---).