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Unifi Controller install woes - Cannot locate Java Home

answers IT are currently on a WatchGuard roll out spree for our clients, and with that comes lots of old hardware - so I decided to salvage a few Ubiquiti devices which had been replaced to test out and find the limits of at home.

I have a Vultr 512MB VPS that is infrequently used (it runs a couple of low traffic WordPress sites). so I opted to run the Unifi Controller on it. Following through the Unifi Controller installation steps was straight forward, and the sheer amount of updates reminded me just how long ago it was since I had logged in (mid 2017!). Everything seemed to install fine, but when trying to reach the controller via the web interface it simply wouldn’t respond.

system start unifi didn’t give any errors. sudo lsof -i -P -n | grep LISTEN didn’t return any the normal open ports however. systemctl status unifi revealed the issue:

Mar 15 10:38:24 tjn-wp-lv01 systemd[1]: Starting unifi...
Mar 15 10:38:24 tjn-wp-lv01 unifi.init[29904]:  * Starting Ubiquiti UniFi Controller unifi
Mar 15 10:38:24 tjn-wp-lv01 unifi.init[29904]: Cannot locate Java Home

A Google search lead me to a post on the Ubiquiti forums to set the JAVA_HOME variable in /etc/init.d/unifi to $( readlink -f "$( which java )" | sed "s:bin/.*$::" )", still no luck.

whereis java revealed that Java was indeed installed, and java -version confirm that openjdk version “9-internal” was in use. Another Google search lead me to yet another post on the Ubiquiti forums which pointed out that the Unifi Controller requires the activation.jar from the JavaBeans Activation Framework - it used to be included in Java SE, but is deprecated in Java 9 and 10, and removed in Java 11.

The path forward was now clear, install Java 8 which includes the JavaBeans Activation Framework - a handful of commands later and the Unifi Controller was up and running, ready to adopt devices:

add-apt-repository ppa:webupd8team/java
apt-get update
apt-get install oracle-java8-installer
apt-get install oracle-java8-set-default
echo JAVA_HOME="/usr/lib/jvm/java-8-oracle" >> /etc/environment
source /etc/environment
systemctl start unifi

Next time I will probably just use Docker…