Before you can start the GUI installer you will need to have working Java environment. Although installer only requires JRE (Java Runtime Environment), server needs the JDK (Java Development Kit). Please do note that currently minimal JDK version Tigase is capable to run on is 1.6. If you don’t have JDK installed it is the right moment to do it. Visit the Java downloads site From the list of available packages select newest JDK version (if you don’t have a specific need to use J2EE then choose a package without it). After configuring JDK you can download the Tigase GUI installer and start the server installation process. It is also important to set the JAVA_HOME environment correctly.