Note: Openfire installers do not contain a bundled Java runtime (JRE). Therefore, you must have a JDK or JRE installed on your system. Openfire 4.3 (also 4.2 and older versions) requires Java 8. Starting with 4.4 version Openfire also supports Java 11. Openfire 4.8 and later require Java 11 and no longer run with older versions of Java. You can check your java version by typing java -version at the command line.