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 On Sat, Aug 2, 2025 at 4:50 PM Kelly Holt <kelly.holt.om...@gmail.com> 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. > Resolved! Thanks for all your comments and help. > Kelly Holt - Omron SQA Manager > > On Friday, August 1, 2025 at 11:26:00 AM UTC-6 Kelly Holt wrote: > >> 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 <goun...@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.ho...@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 >>>>>> >>>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Jenkins Users" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to jenkinsci-use...@googlegroups.com. >>>> To view this discussion visit >>>> https://groups.google.com/d/msgid/jenkinsci-users/c61cacaa-2b22-453f-a6c7-a43b78803cffn%40googlegroups.com >>>> <https://groups.google.com/d/msgid/jenkinsci-users/c61cacaa-2b22-453f-a6c7-a43b78803cffn%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> >>> >>> -- >>> Bruno Verachten >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Jenkins Users" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to jenkinsci-use...@googlegroups.com. >>> >> To view this discussion visit >>> https://groups.google.com/d/msgid/jenkinsci-users/CACtV%3DdfApyZzme8-tchj7Bc3mQUG8icWniF3j%3DKdifhrqR8WJw%40mail.gmail.com >>> <https://groups.google.com/d/msgid/jenkinsci-users/CACtV%3DdfApyZzme8-tchj7Bc3mQUG8icWniF3j%3DKdifhrqR8WJw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- > You received this message because you are subscribed to the Google Groups > "Jenkins Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to jenkinsci-users+unsubscr...@googlegroups.com. > To view this discussion visit > https://groups.google.com/d/msgid/jenkinsci-users/2408f893-4871-46ae-bd6a-3b974411df99n%40googlegroups.com > <https://groups.google.com/d/msgid/jenkinsci-users/2408f893-4871-46ae-bd6a-3b974411df99n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- Bruno Verachten -- You received this message because you are subscribed to the Google Groups "Jenkins Users" group. 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