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Can't connect to X11 window server using ':0.0' as the value of the DISPLAY variable.

Technote (troubleshooting)


When running reports containing charts with a mobile device, the report does not appear in the device's inbox. Reports that do not contain charts appear in the inbox successfully.

In the mob.log:

[mobileThread-3] ERROR - The Mobile service has caught an exception:

java.lang.InternalError: Can't connect to X11 window server using 'xx.xx.xx.xx:0.0' as the value of the DISPLAY variable.


The error occurs when Cognos Mobile is installed on UNIX based environments without graphics support. The Java 'Headless' operation option must be used to allow a Java program to run without a monitor, mouse or keyboard. Headless Java operation would mean that a server side Java program should be able to use the full J2SE or J2EE API without a GUI environment being present. This means that all AWT calls to manipulate components, graphics, fonts, printing etc. should be functional.


AIX, Solaris, HP-UX, Linux

Resolving the problem

Specify the Java headless operation mode on the application server.


  • Weblogic: Edit the startmanagedweblogic file for the Cognos server install and add -Djava.awt.headless=true to the JAVA_OPTIONS section.
  • WebSphere: Edit the server-cfg.xml located in $WAS_ROOT/config. Add -Djava.awt.headless=true to the commandLineArguments="".
  • Tomcat (Cognos default): Edit the bootstrap_<os_type>.xml located in ../c10/bin. Add Add <param>-Djava.awt.headless=true</param> above the entry <param>"-cp"</param>

**Note: The services/application servers need to be restarted for the changes to take effect.

Historical Number


Document information

More support for: Cognos Mobile
Cognos Mobile

Software version: 10.1, 10.1.1, 10.2, 10.2.1

Operating system(s): AIX, HP-UX, Linux, Solaris

Reference #: 1371384

Modified date: 02 October 2013

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