Wiki - FAQ


  1. General Questions
  2. Minimum Requirements
  3. Troubleshooting



Suppressing Warnings

QZ Tray Cost

Installing New Version

Minimum System Requirements

Java Versions

Product Minimum Version
QZ Tray 2.1 Java 8 / OpenJDK 1.8*
QZ Tray 2.0 Java 7 / OpenJDK 1.7*
QZ Tray 1.9 Java 7 / OpenJDK 1.7
QZ Print 1.9 Java 6 / OpenJDK 1.6

*HTML printing in QZ Tray 2.x requires Java 8 + Java FX.

Operating Systems

Operating System Minimum Version
Apple OS X OS X 10.7 Lion or higher*
Microsoft Windows Windows XP or higher*
Linux Ubuntu 12.04 Precise or higher

Version 2.0 or higher requires 512MB of free memory (RAM), recommends 6GB or higher total system memory for raster graphics.

*Safari 5.1.7 is bundled with Lion but is not supported. Alternate browser required.
*Windows XP requires manual certificate installation. Will prompt at install time.

Web Browsers

Web Browser Minimum Version
Safari Safari 6.0.3 or higher
Firefox Firefox 31 or higher*
Chrome Chrome 31 or higher
Internet Explorer IE 10 or higher*
Microsoft Edge 20.x or higher*
* Firefox requires a browser restart for HTTPS
* IE/Edge on domain networks require external DNS access to due to a Local Intranet Limitation.


Debugging QZ Tray

Console Logs

Cannot Launch Software

  1. Sometimes custom JAVA_HOME environmental variables will prevent QZ Tray from loading. If the software can be launched via the command line this is likely the case. In windows this can be checked by going to System > Advanced system settings > Environment Variables

  2. A corrupt Java installation may prevent the software from installing or loading. A corrupt Java installation is fairly common in Windows, and can be resolved by reinstalling Java using the Java offline installer. The offline installer has been reported to fix many issues with corrupt Java installations. Take a look at this guide for our recommended steps on reinstalling Java on all platforms.

    Signs of a corrupt Java install:

    java -version
    "An error has occurred while processing the shared archive file. Unable to unmap shared space. Error occurred during initialization of VM. Unable to use shared archive."

  3. 32-bit vs. 64-bit: Some 64-bit workstations have both 32-bit and 64-bit Java versions installed. If both are needed, make sure both are upgraded, otherwise, removing the 32-bit version is advised to assist with the troubleshooting process.

  4. Insufficient Java Version "A Java Exception has occurred" may appear if attempting to launch against an outdated Java version. For a list of minimum Java requirements see Java Versions.

Cannot List Printers

  1. Mac

    Due to an upstream bug with Java, printer listings may fail on Mac.

    The current workaround is to:

    • Open System Preferences
    • Printers and Scanners
    • Right Click > Reset Printing System
    • Re-add all printers

    We realize this is not ideal, but have found no another work-around on Mac.

  2. Windows

    Although rare, there are scenarios of not being able to list printers, only being able to list one printer, or listing printers takes several minutes to complete. This is likely caused by a driver conflict between the offending printer driver and the print spooler, resulting in the entire print subsystem to hang.

    The workaround is to remove the offending printer or printer driver.

Raw Printer Queues

If your thermal or label printer has undesired results, it may be improperly configured. Here are our tutorials for setting up a printer to receive raw languages on each platform:

Note: Some Windows drivers, such as Zebra's ZDesigner driver for Microsoft Windows, will support raw printing alongside pixel-based/PostScript printing. You may use those drivers or a raw-generic/text-only driver to send raw commands, but the generic driver will not be able to print images/PDF/HTML.

Debugging WebSockets

By default, QZ Tray suppresses verbose websocket information from the console, however occasionally this information may be useful for debugging/troubleshooting connectivity issues.

Debugging WebSockets in 2.0
Debugging WebSockets in 1.9

Socket Disconnected

Other Errors

Invalid JSON

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