Linux Headless: Unable to start JavaFX service #1387
Description
QZ Tray 2.2.5 fails to print HTML content on a Headless Linux server
Steps:
- Install Ubuntu 24.04 Server
- Install
cups-pdfandcups-bsdpackages - Install the
PDFprinter:sudo lpadmin -p PDF -v cups-pdf:/ -E
- Install QZ Tray
curl qz.sh | bash - Configure
setSignaturePromiseandsetCertificatePromiseto use DEMO keys - Copy the demo cert to the Ubuntu Server
/opt/qz-tray/override.crt - Start QZ Tray on the Ubuntu Server
- Connect
sample.htmlto the Ubuntu Server's IP address
- From the "Pixel" tab, click "Print HTML"
WARNING: Unsupported JavaFX configuration: classes were loaded from 'unnamed module @c1a4620'
Exception in thread "Thread-88" java.lang.UnsupportedOperationException: Unable to open DISPLAY
at com.sun.glass.ui.gtk.GtkApplication.lambda$new$6(GtkApplication.java:202)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at com.sun.glass.ui.gtk.GtkApplication.<init>(GtkApplication.java:200)
at com.sun.glass.ui.gtk.GtkPlatformFactory.createApplication(GtkPlatformFactory.java:41)
at com.sun.glass.ui.Application.run(Application.java:146)
at com.sun.javafx.tk.quantum.QuantumToolkit.startup(QuantumToolkit.java:290)
at com.sun.javafx.application.PlatformImpl.startup(PlatformImpl.java:293)
at com.sun.javafx.application.PlatformImpl.startup(PlatformImpl.java:163)
at com.sun.javafx.application.LauncherImpl.startToolkit(LauncherImpl.java:659)
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:679)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:196)
at java.base/java.lang.Thread.run(Unknown Source)
[ERROR] 2025-12-05T21:33:10,420 @ qz.utils.PrintingUtilities:221
Failed to print
java.lang.UnsupportedOperationException: Unable to start JavaFX service
at qz.printer.action.PrintHTML.parseData(PrintHTML.java:140) ~[qz-tray.jar:?]
at qz.utils.PrintingUtilities.processPrintRequest(PrintingUtilities.java:210) ~[qz-tray.jar:?]
at qz.ws.PrintSocketClient.processMessage(PrintSocketClient.java:328) ~[qz-tray.jar:?]
at qz.ws.PrintSocketClient.lambda$onMessage$0(PrintSocketClient.java:174) ~[qz-tray.jar:?]
at java.base/java.lang.Thread.run(Unknown Source) [?:?]
Caused by: java.io.IOException: JavaFX did not start
at qz.printer.action.html.WebApp.initialize(WebApp.java:213) ~[qz-tray.jar:?]
at qz.printer.action.PrintHTML.parseData(PrintHTML.java:71) ~[qz-tray.jar:?]
... 4 more