Windows

Stop Tomcat

Stop Tomcat

Install new Java version

Follow instructions to install Java: Install Java

Update JAVA_HOME

If you have 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.

Update service wrapper

Find the file jvm.dll in the Java installation.

• Java 8: this will be in JAVA_HOME\jre\bin\server\jvm.dll

• Java 11: this will be at JAVA_HOME\bin\server\jvm.dll

Open Tomcat Properties window.

Go to the Java tab. Update the Java Virtual Machine setting to the new location of jvm.dll.

Open

If you have moved between major versions of Java (e.g. you are moving from Java 8 to Java 11), update the Java arguments as instructed here: Install Tomcat on Windows

Remove old version

Installation of a new patch of Java should replace the previous version.

If you are migrating to a new major version of Java (e.g. you are moving from Java 8 to Java 11), you will need to remove the previous version from the list of installed programs.

Start Tomcat

Start Tomcat

Linux

Stop Tomcat

Stop Tomcat

Minor (patch) upgrades

If you have installed Java as recommended by PhixFlow (Install Java), upgrade Java as recommended for any package installed using the package manager. For example, on Debian based distributions of linux, the generally recommended approach is by using dist-upgrade.

Major upgrades

If you are upgrading between major versions of Java, you will need to remove the current installation of Java, and install the new version.

Remove the existing Java installation using the standard method for packages installed using the package manager. For example, on Debian based distributions, to remove Java 8 Adoptium OpenJDK, use the commands:

Then install the new version of Java using the instructions given at , starting from sudo apt-get update (you do not need to re-install or update the Adoptium repository).

Update service script

You may need to update the JAVA_HOME setting in the service script for Tomcat.

To find the new setting, run the command:

This will give you the full path of the java program, for example: /usr/lib/jvm/temurin-11-jdk-amd64/bin/java. The installation directory in this case is /usr/lib/jvm/temurin-11-jdk-amd64.

Check whether this is different from the current setting of JAVA_HOME in /etc/systemd/system/tomcat.service. If this is different, update /etc/systemd/system/tomcat.service to use the new setting for JAVA_HOME, and before you restart the tomcat process, run the command:

Moving from Java 8 to Java 11

If you have moved from Java 8 to Java 11, update CATALINA_OPTS in /etc/systemd/system/tomcat.service as instructed here:

Start Tomcat

Start Tomcat