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Follow instructions to install Java: Install Java
Update JAVA_HOME
If you have Setting JAVA_HOME is not part of the standard installation of Java for PhixFlow, but some operators set this for use with other programs on the same server.
If someone has set the environment variable JAVA_HOME, check whether this needs updating in the system environment variables. Commonly this will be automatically updated by the installation process.
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If you have moved from Java 8 to Java 11, update CATALINA_OPTS in /etc/systemd/system/tomcat.service for the the new logging settings at that version of Java, as instructed here: Install Tomcat on Linux
Start Tomcat
See https://phixflow.atlassian.net/wiki/pages/createpage.action?spaceKey=HELPTRUNKR&title=Tomcat%20start%2F%20stop%2C%20open%20properties&linkCreation=true&fromPageId=8576270352 Managing Tomcat