Java 21.x Upgrade (Windows)

Upgrading the Java Development Kit (JDK) is critical for maintaining security, performance, and compatibility with modern Java applications. This document provides step-by-step instructions for upgrading Java to JDK 21.x on a Windows machine, reconfiguring environment variables, and reintegrating the JDK with an existing Apache Tomcat service.

Prerequisites

Before starting the upgrade, ensure the following:

• Administrator access to the Windows machine.

• Backup of the current Tomcat configuration, including Java Options and Heap Size.

• Tomcat service is stopped before the upgrade.

• Internet access available to download the JDK installer.

Upgrade Process Steps

1. Stop and Backup Tomcat Configuration

   • Open Services → Locate the Tomcat service → Right-click → Stop.

     
   • Navigate to the Tomcat bin directory.

     
   • Open Command Prompt in that directory and run:

     Copy

     tomcat10w.exe //ES//<TomcatServiceName>

     Sample Reference Screenshot:

     

     (Replace <TomcatServiceName> with your actual Tomcat service name).

   • In the Java tab, note down:

     • Java Options

     • Heap Size values (Copy to a Notepad for later reference).

   • Uninstall the existing Tomcat service:

     Copy

     service.bat remove <TomcatServiceName>

     Sample Reference Screenshot:

     

1. Uninstall Previous JDK Version

   • Open Control Panel → Programs → Programs and Features.

   • Locate the existing Java/JDK installation.

   • Right-click → Uninstall.

2. Download and Install JDK 21.x

   • Download the installer: OpenLogic JDK 17.0.15+6 MSI (Windows x64)

   • Run the .msi installer.

   • Follow the setup wizard to complete the installation.

3. Set Environment Variables

   • Press Windows Key → Search for Environment Variables → Open Edit the system environment variables.

     
   • Click Environment Variables.

     

     • Under System Variables → New:

       • Variable Name: JAVA_HOME

       • Variable Value:

         

         
     • Under System Variables → Path → Edit: Ensure the following entry exists (if not already present):
4. Verify Java Installation

   • Open Command Prompt and run:

   • Expected output:

     Sample Reference Screenshot:

     
5. Reconfigure Tomcat Service

   • Navigate to Tomcat’s bin directory:

   • Reinstall the Tomcat service:

   • Open Tomcat configuration:

     Sample Reference Screenshot:

     
   • Under the Java tab:

     • Restore previously saved Java Options and Heap Size.

     • Update paths if necessary (e.g., to extprop or log4j.properties).

       
   • Under the General tab:

     • Set Startup Type → Automatic (Delayed Start).

       
   • Return to Services → Locate Tomcat service → Start.

     

Validation

After Tomcat is started:

• Review catalina.out or stdout/stderr logs for errors.

• Confirm application accessibility through the web interface.

• Verify environment variables:

• Ensure it points to the new JDK directory.

Copyright © 2025, OvalEdge LLC, Peachtree Corners, GA, USA.