Java 17 (jdk17) end of life

[Maciej Jaros]

I received a message about "Java 17 end of life in Jenkins." I assume this means I should install JDK21 ASAP, right? The docs don't seem to be ready for that, though.

This still only mentions JDK17:

• https://www.jenkins.io/doc/book/installing/linux/
• https://www.jenkins.io/doc/book/installing/linux/#installation-of-java

Update the Debian apt repositories, install OpenJDK 17, and check the installation with the commands:
...

I would assume it should now suggest using JDK21, right?

Even platform information only talk about upgrades to JDK11 and JDK17:
https://www.jenkins.io/doc/book/platform-information/

Java support and upgrade information

In addition to support policies, this chapter provides information on upgrading your Java version in Jenkins. Depending on your current Java version, there are instructions for upgrading to Java 11 and upgrading to Java 17.

Java support policy does mention JDK21, but doesn't mention a version that would break support with JDK17
https://www.jenkins.io/doc/book/platform-information/support-policy-java/index.html

Perhaps the message was sen too early in Jenkins 2.492.3?

Regards,
Maciej Nux.

[Ullrich Hafner]

Yes, you are right. It makes sense to switch to Java 21 in the next couple of months (actually I never understood why one should not directly move from Java 11 to Java 21 for the controllers, as we also fully support Java 21 from the beginning of the Java 17 switch). The plan is to switch the weekly Jenkins releases to Java 21 in the middle of this year. 

See https://www.jenkins.io/blog/2023/11/06/introducing-2-2-2-java-support-plan/

If you find such wrong references of the Java version in out documentation it would be helpful if you can either create an issue in Jira or even better: click the „Improve the page“ button and fix the corresponding page by yourself. This helps us a lot as the documentation is spread along a lot of different files...

Ulli

[Dirk Heinrichs]

Am Mittwoch, dem 09.04.2025 um 20:07 +0200 schrieb 'Maciej Jaros' via Jenkins Users:

I received a message about "Java 17 end of life in Jenkins." I assume this means I should install JDK21 ASAP, right?

Why? It clearly says: May 2026.

HTH...

Dirk

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[Adrien Lecharpentier]

Hello,

yes this is odd that you got the administrative monitor warning you about the JVM version that you are using.

The code, as Dirk said, is stating March 2026: https://github.com/jenkinsci/jenkins/blob/37085d6db7474499d4df1aa0ba610544c7252159/core/src/main/java/jenkins/monitor/JavaVersionRecommendationAdminMonitor.java#L81.

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[Daniel Beck]

On Thu, Apr 10, 2025 at 10:48 AM Adrien Lecharpentier <adrien.lec...@gmail.com> wrote:

yes this is odd

The warning is optimized for crap orgs that take an entire year to update their Java version.

[Maciej Jaros]

'Dirk Heinrichs' via Jenkins Users (2025-04-10 08:56):

Am Mittwoch, dem 09.04.2025 um 20:07 +0200 schrieb 'Maciej Jaros' via Jenkins Users:

I received a message about "Java 17 end of life in Jenkins." I assume this means I should install JDK21 ASAP, right?

Why? It clearly says: May 2026.

Well, it is bright orange and looks like a warning... and I have to "dismiss" it rather than just mark it as read. It does seem like something for which an action is required. While I guess there is no other way to frame it, it would probably be helpful to have options like "remind me later," "remind me in a month," or "remind me by the end of summer." ;)

Clicking on a link in the warning I see no further information, so that leaves too much space to speculate on what that message actually means. I think it would be helpful to add a link either to this post: https://www.jenkins.io/blog/2023/11/06/introducing-2-2-2-java-support-plan/ (which does explain some things), or link to some new blog post.

Cheers,
Maciej Nux

[Maciej Jaros]

Ullrich Hafner (2025-04-09 21:05):

Yes, you are right. It makes sense to switch to Java 21 in the next couple of months (actually I never understood why one should not directly move from Java 11 to Java 21 for the controllers, as we also fully support Java 21 from the beginning of the Java 17 switch). The plan is to switch the weekly Jenkins releases to Java 21 in the middle of this year. 

See https://www.jenkins.io/blog/2023/11/06/introducing-2-2-2-java-support-plan/

If you find such wrong references of the Java version in out documentation it would be helpful if you can either create an issue in Jira or even better: click the „Improve the page“ button and fix the corresponding page by yourself. This helps us a lot as the documentation is spread along a lot of different files...

The link does explain a bit, thanks. It talks about dropping JDK11, though.

As for the docs updates, I really don't know what problems come with the upgrade, so I can't write about that. Should I expect everything to just work? Will all plugins work? Is there a tester script for this? Are popular plugins tested with various versions of Java automatically?

I saw the video on upgrading to JDK17 (linked in the docs), and it just talks about how to check my Java version and how to make sure the main node and builder nodes use the same Java version (which is helpful but doesn't explain much). It does seem like a very manual process to verify the upgrade.

Cheers,
Maciej Nux

[Kevin Martens]

Hi Maciej,

Thanks for raising this issue. I wanted to share that I've gone through the jenkins.io documentation and believe I have created or updated all the documentation spots for Java 21. This includes Java 21 upgrade instructions, an update to the platform information page to include Java 21, various installation documentation being updated to use images with Java 21 such as Linux and Docker, and any area that would have previously used Java 17. If there are any other areas of documentation that need to be updated accordingly, please let me know and I'd be happy to make sure that everything is current.

Thanks very much,

Kevin Martens, Jenkins Documentation Officer

[Kelly Holt]

I'm stumped here. I got the same warning message and have followed the instructions found on the link [Java 21 upgrade instructions], but when I go to start Jenkins, it fails. The logs are not much help other than Jenkins failed to start. Using update-alternatives to set the JDK back to Ubuntu's OpenJDK-17-jdk, then Jenkins server starts as expected. Am I missing something here? Is there something wrong with my installation? I also tried Openjdk-21-jdk from Ubuntu default installation and I get the same issue: Jenkins fails to start.

Any help is appreciated.
Kelly Holt

[Verachten Bruno]

Hello Kelly,

Thank you for reaching out and sharing the details of your issue.
Could you let us know which version of Jenkins you are trying to run with JDK 21?
Any recent LTS version should generally work without any issues. If you're using a non-LTS version or an older release, that might explain the problem you're encountering.
Additionally, it could be helpful to double-check the compatibility of any plugins you have installed, as certain plugins might not yet fully support JDK 21. If you haven't already, reviewing the Jenkins logs in detail might provide more clues, even if the initial error message seems vague.

Best regards,
Bruno  Verachten

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[Kelly Holt]

I am using OpenJDK-17

[openjdk version "17.0.15" 2025-04-15

OpenJDK Runtime Environment (build 17.0.15+6-Ubuntu-0ubuntu124.04)

OpenJDK 64-Bit Server VM (build 17.0.15+6-Ubuntu-0ubuntu124.04, mixed mode, sharing)]

dpkg -l shows:

ii  openjdk-17-jdk:amd64               17.0.15+6~us1-0ubuntu1~24.04            amd64        OpenJDK Development Kit (JDK)

ii  openjdk-17-jdk-headless:amd64      17.0.15+6~us1-0ubuntu1~24.04            amd64        OpenJDK Development Kit (JDK) (headless)

ii  openjdk-17-jre:amd64               17.0.15+6~us1-0ubuntu1~24.04            amd64        OpenJDK Java runtime, using Hotspot JIT

ii  openjdk-17-jre-headless:amd64      17.0.15+6~us1-0ubuntu1~24.04            amd64        OpenJDK Java runtime, using Hotspot JIT (headless)

Jenkins Server Version is 2.504.1

I'll have to try to switch it again after working hours. The Jenkins server is currently needed to run several builds.

To view this discussion visit https://groups.google.com/d/msgid/jenkinsci-users/CACtV%3DdfApyZzme8-tchj7Bc3mQUG8icWniF3j%3DKdifhrqR8WJw%40mail.gmail.com.

[Kelly Holt]

This was a tough nut to crack. I updated the LTS jenkins version I had running to 2.516.1 LTS and started jenkins. It started but was using JDK-17. As I had JDK-21 still installed, I stopped jenkins service, used update-alternatives --config java to set it to jdk-21. When I started the new jenkins LTS version with jdk-21, it worked. So, there must have been some incompatibility in 2.504.1 and jdk-21.
Resolved! Thanks for all your comments and help.
Kelly Holt - Omron SQA Manager

[Verachten Bruno]

Hi Kelly,

Thank you for sharing your experience and the solution you found to the issue with the JDK-21 in Jenkins.
It's great to hear that updating to version 2.516.1 LTS and switching to JDK-21 resolved the compatibility issue you were facing.

Your insights and detailed explanation will be helpful for others in the community who might encounter similar challenges. We appreciate you taking the time to share your solution.

Best regards,

Bruno Verachten

To view this discussion visit https://groups.google.com/d/msgid/jenkinsci-users/2408f893-4871-46ae-bd6a-3b974411df99n%40googlegroups.com.

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[Mark Waite]

On Saturday, August 2, 2025 at 8:49:45 AM UTC-6 Kelly Holt wrote:

This was a tough nut to crack. I updated the LTS jenkins version I had running to 2.516.1 LTS and started jenkins. It started but was using JDK-17. As I had JDK-21 still installed, I stopped jenkins service, used update-alternatives --config java to set it to jdk-21. When I started the new jenkins LTS version with jdk-21, it worked. So, there must have been some incompatibility in 2.504.1 and jdk-21.

I'm glad that the issue is resolved for you, but I'm not aware of any incompatibility between Jenkins 2.504.1 and Java 21 in any configuration.  I ran 2.504.1 with Java 21 on Linux in a Docker container for multiple weeks after its release.  Others run Jenkins from installation packages with Java 21 on Amazon Linux 2023, Red Hat Enterprise Linux 8 and 9, Debian Linux 11 and 12, Ubuntu 22.04 and 24.04, and more.  Automated testing of the installation process uses Java 21 to check that it installs as part of the LTS release checklist.  I'm not aware of any reported issues with Jenkins 2.504.1 and Java 21.  

The Jenkins usage statistics for the last full month of reported data shows over 47000 installations that are running Jenkins with Java 21.

Can you provide enough details so that others can duplicate the failure?

 

Thanks,

Mark Waite