2.541 as 21 Jan 2026 LTS baseline

[Jenkins Developers]

It is time to choose the next LTS baseline.  The first release of that LTS baseline is scheduled for 21 Jan 2026.

I recommend Jenkins 2.541, released today.  Includes security fixes.

Mark Waite

[Ullrich Hafner]

Isn’t it also time to switch the Java baseline to JDK 21 now?

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[Kris Stern]

I would second that, as the Java JDK baseline should definitely be shifted to 21...

Best,

Kris

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From: jenkin...@googlegroups.com <jenkin...@googlegroups.com> on behalf of Ullrich Hafner <ullrich...@gmail.com>
Sent: 12 December 2025 16:57
To: Jenkins Developers <jenkin...@googlegroups.com>
Subject: Re: 2.541 as 21 Jan 2026 LTS baseline

 

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[Tim Jacomb]

Java 21 is planned for the LTS after this if I'm not mistaken:

https://github.com/jenkinsci/jenkins/blob/67db13142a68679b728c332098f9b3a5b6a8d882/core/src/main/java/jenkins/monitor/JavaVersionRecommendationAdminMonitor.java#L81

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[Jenkins Developers]

On Friday, December 12, 2025 at 1:57:39 AM UTC-7 Ullrich Hafner wrote:

Isn’t it also time to switch the Java baseline to JDK 21 now?

That's a very good question.  The Java 17 end of life administrative monitor that we display to Java 17 users  says that support for Java 17 will end March 31, 2026.  If we want the first LTS baseline that releases after March 31, 2026 to drop support for Java 17, then we need to start the work in Jenkins weekly now so that it can be available in a Jenkins weekly release before the next LTS baseline is selected.  The next LTS baseline is scheduled to be selected March 4, 2026.

Do we think that we can complete the work to drop support for Java 17 from Jenkins weekly before March 4, 2026?

Mark Waite

[Tim Jacomb]

> Do we think that we can complete the work to drop support for Java 17 from Jenkins weekly before March 4, 2026?

Yes, that should be fine.

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[Ullrich Hafner]

Java 17 users  says that support for Java 17 will end March 31, 2026

This is the support for Java from Oracle, but not our support. 

I think we should not wait another four months, we are already late in our plan:

We agreed in a long discussion to switch to Java 21 this year and that already was a compromise (actually we planned to switch to Java 21 right after the drop of Java 11). So I think we should stick to that plan (that has been accepted by the Governance board) and drop Java 17 the next weekly after the next LTS baseline switch. This is already later than planned. I also did not hear any complaint from users that still want to use the Java 17 runtime so why should we wait for that step again. Java 21 support ist already available for two years now. 

Ulli

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[Mark Waite]

On Sat, Dec 13, 2025 at 6:04 AM Ullrich Hafner <ullrich...@gmail.com> wrote:

I think we should not wait another four months, we are already late in our plan:

We agreed in a long discussion to switch to Java 21 this year and that already was a compromise (actually we planned to switch to Java 21 right after the drop of Java 11). So I think we should stick to that plan (that has been accepted by the Governance board) and drop Java 17 the next weekly after the next LTS baseline switch. This is already later than planned. I also did not hear any complaint from users that still want to use the Java 17 runtime so why should we wait for that step again. Java 21 support ist already available for two years now. 

When you say that we should "drop Java 17 in the next weekly after the next LTS baseline switch",  I assume you mean 2.541 as the next LTS baseline switch.  The 2.541.1 release is scheduled for Jan 21, 2026.

If that assumption is correct, then I think that your idea matches mine.  The 2.541.1 LTS will support Java 17 because 2.541 weekly supports Java 17.   Weekly releases after 2.541 can drop support for Java 17 so that the LTS baseline selected on March 4, 2026 will not support Java 17.  Someone (who?) can submit the pull requests necessary to drop Java 17 support from a Jenkins weekly release after 2.541.  The new LTS baseline that releases on April 15, 2026 would be the first LTS to drop support for Java 17.

Mark Waite

[Ullrich Hafner]

Maybe we should not use dates and discuss weekly release numbers;-) I was irritated about your March deadline.

I am fine with using 2.541 as latest baseline for the LTS that supports Java 17. 

Weekly releases 2.54x where x is 2, 3 or another small number should switch to Java 21 as baseline (whenever a PR has been created, is there a similar PR available for the Java 11 -> Java 21 switch?). We should not wait for March to make the transition to have time to fix potential problems.

That means, plugins can start to switch to Java 21 soon when they use this new Java 21 Jenkins weekly baseline version. 

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