FAQ

Compatibility

• ✅ 2.0 | ✅ 1.9 | ...

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1. General Questions

• How does the certificate licensing work?
• How do you suppress print warning dialogues?
• How much does QZ Tray cost?
• Can a new version be installed on top of an old version?
• Does QZ Tray support HTTPS?

1. Minimum Requirements

• Java
• OS
• Browser

1. Troubleshooting

• How do I debug QZ Tray?
• Why won't QZ Tray load?
• Why can't I list my printers?
• How do I debug WebSockets?
• Why do I receive invalid JSON?

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General

Licensing

• When you purchase Premium Support you are granted the ability to generate an Intermediate Certificate and a public/private key pair to suppress all warning dialogues. This certificate has:

• No client/user limitations

• No domain restrictions

A single license will suffice for 99% of organizations

• The purchase of the premium version also provides technical support for one year. The Technical Support Team of QZ Industries, LLC will work diligently to help integrate the software into your environment. All questions are promised to be answered as fast as possible (usually well within a 24-hour period).

Suppressing Warnings

• In order to suppress print warning dialogues, all print requests must be signed using the Intermediate Certificate and private key. An in-depth tutorial explaining how to do this can be found here.

QZ Tray Cost

• QZ Tray is free. Organizations wishing to print silently are required to purchase a certificate from QZ Industries, LLC or implement their own root certificate. Pricing options can be found on QZ's homepage at https://qz.io.

Installing New Version

• Installation of a new version will succeed even if an older version is present and/or running.
• Note: QZ Tray 2.0 is not backwards compatible with QZ tray 1.9.

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Minimum System Requirements

Java Versions

Product	Minimum Version
QZ Tray	Java 7 / OpenJDK 1.7*
QZ Print	Java 6 / OpenJDK 1.6

*HTML printing in QZ Tray 2.0 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

*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 Automatically detect intranet network unchecked.

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Troubleshooting

Debugging QZ Tray

• The recommended approach for getting verbose output from QZ Tray is to launch the software from command line. This will expose the Java Console with detailed information about debug messages and exceptions including full backtrace of where a particular exception occurred.

• QZ Tray launches with 512MB of memory. We must specify -Xms512M in the command in order to prevent unexpected behavior and crashing. This unnecessary for Mac unless following the basic syntax (java -jar qz-tray.jar) . More memory can be allocated but should not be necessary.

  Basic syntax

  java -Xms512M -jar qz-tray.jar

  Windows

  java -Xms512M -jar "%PROGRAMFILES%\QZ Tray\qz-tray.jar"

  Mac OS X

  /Applications/QZ\ Tray.app/Contents/MacOS/QZ\ Tray

  Linux/Other

  java -Xms512M -jar /opt/qz-tray/qz-tray.jar

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 loading. A corrupt Java installation is fairly common in Windows, and can be resolved by reinstalling Java. We recommend using a Java offline installer when reinstalling.

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.

1. 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.

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

• 2.0 Only - Using the qz.api.showDebug(...) API option, verbose connection details will logged to the browser's console.

qz.api.showDebug(true);  // must be called prior to calling qz.websocket.connect()

Debugging WebSockets in 1.9

• 1.9 Only - Using the deployQZ(...) API option, verbose connection details will logged to the browser's console.

deployQZ(null, true);  // usage: deployQZ(hostname, debug);

Invalid JSON

• If the browser console says Invalid JSON, try changing your HTTP headers in the sign-message example to use text/plain instead of application/json. In PHP, this is done via:

  - header('Content-Type: application/json');
  + header('Content-Type: text/plain');

Note: This technique will vary depending on the server-side language being used.

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