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This is often caused by running your web app container (ex: tomcat) under a SUN Oracle JDK or JRE that is not version 1.5.0 update 8 or later. Verify that you are running with the required JDK or JRE. If not, to solve this, download & install JDK or JRE 1.5.0 version 8 or later from http://www.sun.com. Set your JAVA_HOME on windows to the JDK or JRE install directory on your computer. Then restart your web app container.

This may also be caused by an incorrect string content in the license key.  To check the license, login via superuser and then click "Server Configuration". You can also check the users schema resource table in your database. This table has an entry with the license information. 

Unable to contact license server

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