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.
On Fri, Aug 1, 2025 at 9:23 AM Verachten Bruno <gount...@gmail.com> wrote:
> 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
>
> On Fri, Aug 1, 2025 at 5:15 PM Kelly Holt <kelly.holt.om...@gmail.com>
> wrote:
>
>> I'm stumped here. I got the same warning message and have followed the
>> instructions found on the link [Java 21 upgrade instructions
>> <https://www.jenkins.io/doc/book/platform-information/upgrade-java-to-21/>],
>> 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
>> On Tuesday, April 29, 2025 at 4:39:34 PM UTC-6 Kevin Martens wrote:
>>
>>> 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
>>> <https://www.jenkins.io/doc/book/platform-information/upgrade-java-to-21/>,
>>> an update to the platform information page
>>> <https://www.jenkins.io/doc/book/platform-information/> to include Java
>>> 21, various installation documentation being updated to use images with
>>> Java 21 such as Linux
>>> <https://www.jenkins.io/doc/book/installing/linux/> and Docker
>>> <https://www.jenkins.io/doc/book/installing/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
>>>
>>> On Thursday, April 10, 2025 at 6:34:22 AM UTC-4 maciej wrote:
>>>
>>>> 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
>>>> <https://www.jenkins.io/doc/book/platform-information/upgrade-java-to-17/index.html>),
>>>> 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
>>>>
>>> --
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>>
>
>
> --
> Bruno Verachten
>
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