Launcher Crash on Linux: Unable to open DISPLAY (JavaFX)

What it looks like in the log

java.lang.UnsupportedOperationException: Unable to open DISPLAY

How to fix it

1. Run `echo $DISPLAY` in the same terminal you use to start the launcher; if it prints nothing, launch the JAR from a graphical desktop terminal as your normal user (do not use `sudo` or a text TTY).
2. If you use a Wayland compositor (such as Weston, Sway, or GNOME Wayland), ensure `xwayland` is installed and enabled, or switch to an Xorg/X11 session at your Linux login screen.
3. Close background applications known to leak X11 connections over time (such as Linux QQ or long-running Flatpak apps), or log out and log back into your desktop session to reset the X server client limit.
4. Reinstall the full desktop OpenJDK package rather than a headless runtime (for example, `sudo apt install --reinstall openjdk-21-jdk` on Ubuntu/Debian/Zorin OS).

Check your own log