I am currently trying to install Forge onto my computer. I run 64-bit Fedora 29. I downloaded the forge installer .jar file, and tried to run it from terminal using the java -jar jarfile command. I've done this before, and it worked - however I've reinstalled the OS since then and I've had trouble running jar files for some reason. When I execute the command, the system creates a .jar.log file and this is the output: java.net.preferIPv4Stack=true Exception in thread "main" java.awt.HeadlessException at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:204) at java.awt.Window.<init>(Window.java:536) at java.awt.Frame.<init>(Frame.java:420) at net.minecraftforge.installer.InstallerPanel.run(InstallerPanel.java:411) at net.minecraftforge.installer.SimpleInstaller.launchGui(SimpleInstaller.java:162) at net.minecraftforge.installer.SimpleInstaller.main(SimpleInstaller.java:135) I checked the properties of the jarfile and the permission to allow it to execute as a program is checked, and it still won't run the installer. Does anybody know how to fix this? EDIT: Apparently this is an issue with Linux using two versions of java. Ran the command $ sudo dnf install java-1.8.0-openjdk, seems to work fine now.