Single sign-on supports the Java Runtime Environment (JRE), Versions 1.4.x, 5 (1.5.x), and 6 (1.6.x). Download the current supported version from the Sun Microsystems Web site (http://java.sun.com).
You might see the following error message when you attempt to install or uninstall the plug-in:
"Citrix Single sign-on has detected that one or more Java software programs or files are currently in use. Please close all programs and stop all Java-related services before continuing. "
Typically, this error occurs if you are installing the plug-in on a computer also running a Web server service such as Apache Tomcat or Apache HTTP server. Also, this error might be seen if you are installing the plug-in on a XenApp server with a License Management Console installed.