Last checked and updated on 03 May 2026What Is New in Jenkins 2.426.x
Jenkins 2.426.x LTS delivers major platform modernization, significant UI updates, and crucial infrastructure improvements. This release focuses on removing legacy dependencies, enhancing security, and improving the overall user experience.
| Category | Key Changes |
|---|---|
| New Features | Java 21 support, Appearance system configuration, Prototype.js removal |
| Improvements | UI modernization, Content Security Policy compliance, Telemetry additions |
| Bug Fixes | Form validation fixes, Agent allocation issues, Memory leak resolution |
| Security | Security advisories addressed, HTTP header enhancements |
| Deprecated/Removed | Prototype.js library, System V init scripts, CentOS 7 container images |
What major dependencies were removed in this release?
Jenkins 2.426.x completely removes the Prototype.js JavaScript library from core. This is a significant architectural change that eliminates a legacy dependency dating back to Jenkins' early days.
The removal required extensive work across the plugin ecosystem to ensure compatibility. Several plugins with substantial installation counts still need updates to remove their Prototype dependencies. This change improves security and paves the way for modern JavaScript development practices.
How does Java 21 support affect my Jenkins installation?
Jenkins 2.426.1 adds official support for Java 21 alongside existing Java 11 and 17 support. This means you can run Jenkins on the latest Java LTS version with full compatibility.
Container images now use Java 17 as default for tags without explicit JDK specification. If you need to maintain Java 11 compatibility, you must use specific tags like jenkins/jenkins:2.426.1-jdk11. The Java 21 support covers all distribution methods including WAR files, native packages, and container images.
What UI and UX improvements were introduced?
This release includes comprehensive UI modernization across multiple areas. Buttons, menus, link designs, and content blocks received visual updates for a more consistent and modern appearance.
The new Appearance system configuration page allows administrators to customize Jenkins' look and feel. Form validation was fixed to properly show errors for initially hidden elements, resolving long-standing usability issues. Context menus and build history views were also restored and improved.
What security enhancements should I be aware of?
Multiple security advisories were addressed across the 2.426.x release series. The Content Security Policy compatibility was significantly improved, particularly for workspace and artifact browsers.
Security-related HTTP headers were added to agent listener responses to address scanner false positives. The update also includes upgraded dependencies with security fixes, including Jetty and various Spring Framework components.
What infrastructure changes affect deployment?
The minimum required Remoting version was increased to 4.13. Agents running older Remoting versions will be rejected unless explicitly allowed via system property. This ensures all agents meet current security and compatibility standards.
System V initialization scripts were completely removed from RPM packages, requiring systemd for service management. CentOS 7 container images were discontinued following Red Hat Enterprise Linux 7's end of life, pushing users toward newer operating system versions.
FAQ
Will my existing plugins work with Jenkins 2.426.x?
Most plugins will work, but those depending on Prototype.js need updates. Check the plugin compatibility sheet before upgrading.
How do I handle the Remoting version requirement change?
Ensure all agents run Remoting 4.13 or newer. Use the hudson.slaves.SlaveComputer.allowUnsupportedRemotingVersions system property temporarily if needed.
What happens to my CentOS 7 Jenkins installation?
While Jenkins may still run, official support ended. Migrate to RHEL 8/9, AlmaLinux, Rocky Linux, or other supported platforms.
Does the Appearance configuration affect JCasC?
Yes, JCasC configurations for certain plugins need to move from unclassified to appearance section.
Why was the treeview option removed from artifact lists?
It used inline JavaScript that violated Content Security Policy standards. The list view provides equivalent functionality without security concerns.