# 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**.<br>

     <figure><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXcnZuhGZfkv8PehXFInX5BHZCB0c4Fh3A5xvaaT55Y9ZzNuciVcZa6WJ03OcHX3FLhawQV0mAc9VR8HaSdUMaIviVrcQ8wK9PQOIQTOJc3Iinf8GYf6I-N17lgrxXhfR_PD2cNWeg?key=wsJinZRbAIZ4GlPtfAYaRA" alt=""><figcaption></figcaption></figure>
   * Navigate to the **Tomcat `bin` directory**.

     <figure><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXcSc3wXkYzOShX1-B4lonLSXRdMPUIHkVduIXBlbIDZGkIe8AFAZ_nTbyVv6pC7XL8JUmmdrWFjzHYPvJQTXymRZmitt1DBncnFB6_wZXmdykDIASKJG0AbeYoXd64BezBAgX1Hew?key=wsJinZRbAIZ4GlPtfAYaRA" alt=""><figcaption></figcaption></figure>
   * Open **Command Prompt** in that directory and run:

     ```cmd
     tomcat10w.exe //ES//<TomcatServiceName>
     ```

     \
     *Sample Reference Screenshot:*

     <figure><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXfp9HgGgSiMu88LanZ1JmK_39Hp-B5x6UWDxUhnbCkUPMiRXZ7kE4NlM91aTzBSSBZVmIa-z5CpQJpYuCkiEvs9SLZjC1NlTo_uwnhA1I7H3ny5Tw6Nrz1TB6OYD_x02byLcpA2?key=wsJinZRbAIZ4GlPtfAYaRA" alt=""><figcaption></figcaption></figure>

     \
     *(Replace `<TomcatServiceName>` with your actual Tomcat service name)*.
   * In the **Java tab**, note down:
     * Java Options
     * Heap Size values\
       \&#xNAN;*(Copy to a Notepad for later reference).*
   * Uninstall the existing Tomcat service:

     ```cmd
     service.bat remove <TomcatServiceName>
     ```

     \
     \&#xNAN;*Sample Reference Screenshot:*

     <figure><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXeuqtFx0VNBixxamlBHelJrmj4opXI5eOHHSxb_YgH3dc-BT0EAF9CD5D9yc0FQ_nrxAK3BxLJf9jVuuh68vanj1XMQo851tv4wTkKfy3aeNZTIR062NV2m1pQmSVJfvWHmso_fxg?key=wsJinZRbAIZ4GlPtfAYaRA" alt=""><figcaption></figcaption></figure>

2. Uninstall Previous JDK Version
   * Open **Control Panel** → Programs → Programs and Features.
   * Locate the existing **Java/JDK installation**.
   * Right-click → **Uninstall**.<br>

3. Download and Install JDK 21.x
   * Download the installer:\
     [OpenLogic JDK 17.0.15+6 MSI (Windows x64)](https://ovaledge.s3.us-west-1.amazonaws.com/scripts/packages/openlogic-openjdk-17.0.15.6-windows-x64.msi)
   * Run the **.msi installer**.
   * Follow the setup wizard to complete the installation.<br>

4. Set Environment Variables
   * Press **Windows Key** → Search for **Environment Variables** → Open **Edit the system environment variables**.

     <figure><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXcfwADKKNk7hWARvMfOuvjuTiOx8epfaK7PliVZAufZvjFzMQ8KW6a4efKJTlMRFnKKdgtDL_yaM7nh737b9sNG79YEpObarpyJRGS3hAAWcUXdEoLmOG4BvWfzUQt1dVN6HF3z1w?key=wsJinZRbAIZ4GlPtfAYaRA" alt=""><figcaption></figcaption></figure>
   * Click **Environment Variables**.

     <figure><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXc-DneOkByAHhFFl6AdK0FiI9GuLkFPu5mB9j4dv-eeZKre5KZkLWKK4wCbAIvl33m4J-c5m9IYE4sAeXr63yhe5O6yT0Hn_6APEmvAwlFEZCrQgiT1QmdtqewhKqJ7IZMVbL3EsA?key=wsJinZRbAIZ4GlPtfAYaRA" alt=""><figcaption></figcaption></figure>

     * Under **System Variables → New**:
       * **Variable Name:** `JAVA_HOME`
       * **Variable Value:**&#x20;

         ```
         C:\Program Files\OpenLogic\jdk-21.x.x.x-hotspot
         ```

         <figure><img src="/files/z7yFYdjkkvwJ1NGGOWvE" alt=""><figcaption></figcaption></figure>

         <figure><img src="/files/Hc7UWCQ0dNY9rp7T4PJT" alt=""><figcaption></figcaption></figure>
     * Under **System Variables → Path → Edit**:\
       Ensure the following entry exists (if not already present):
       * ```
         C:\Program Files\OpenLogic\jdk-21.x.x.x.x-hotspot\bin
         ```

5. Verify Java Installation
   * Open **Command Prompt** and run:

     ```cmd
     java -version
     ```
   * Expected output:

     ```
     openjdk version "21.x.0.15" 2024-04-16
     OpenLogic OpenJDK Runtime Environment ...
     ```

     \
     \&#xNAN;*Sample Reference Screenshot:*<br>

     <figure><img src="/files/cKHjysgjl6gMvvsmstfc" alt=""><figcaption></figcaption></figure>

6. Reconfigure Tomcat Service
   * Navigate to Tomcat’s `bin` directory:

     ```cmd
     cd C:\ovaledge\apache-tomcat-10.1.40\bin
     ```
   * Reinstall the Tomcat service:

     ```cmd
     service.bat install <TomcatServiceName>
     ```
   * Open Tomcat configuration:

     ```cmd
     tomcat10w.exe //ES//<TomcatServiceName>
     ```

     \
     \&#xNAN;*Sample Reference Screenshot:*<br>

     <figure><img src="/files/zR4aqIvSiNrUVh4SqIWi" alt=""><figcaption></figcaption></figure>
   * Under the **Java tab**:
     * Restore previously saved **Java Options** and **Heap Size**.
     * Update paths if necessary (e.g., to extprop or `log4j.properties`).<br>

       <div align="left"><figure><img src="/files/iucOO9kOWs2BvyJZJ7E2" alt=""><figcaption></figcaption></figure></div>
   * Under the **General tab**:
     * Set **Startup Type → Automatic (Delayed Start)**.<br>

       <figure><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXdmmwO-7tjBVHENyKSEzacc43F6bFMA-0ZReouThVPlZyHcBnsA5GgHvlk98t19wKVHXb6-axiD4xaqsb5gQs40FQ4zdSVPmenUHxYutpptqitfSpkGuMND1PqqId2F_dA-6gabxQ?key=wsJinZRbAIZ4GlPtfAYaRA" alt=""><figcaption></figcaption></figure>
   * Return to **Services** → Locate Tomcat service → **Start**.<br>

     <figure><img src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXc-R0KEXldX4bvQ3mm_Sfo2tT8lR4fI3kwnFAaBO6QlalFOpeEhC9fRrj_ARUh3FU73BmLaaDFt2sjEd5fuplQ_Ao79W89tLunCivlpS5mcDxZo-pJv2MLZxmqdm5n6TuEFIez4Mg?key=wsJinZRbAIZ4GlPtfAYaRA" alt=""><figcaption></figcaption></figure>

## Validation

After Tomcat is started:

* Review **catalina.out** or **stdout/stderr logs** for errors.
* Confirm application accessibility through the web interface.
* Verify environment variables:

  ```cmd
  echo %JAVA_HOME%
  ```
* Ensure it points to the new JDK directory.

***

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


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