Last checked and updated on 03 May 2026What Is New in Jenkins 2.504.x
Jenkins 2.504.x brings significant UI modernization, library updates, and performance improvements. The headline change is the removal of the legacy Yahoo! UI (YUI) library, marking a major step in the platform's modernization.
| Category | Key Changes |
|---|---|
| Major Enhancements |
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| UI & UX Improvements |
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| Library & Dependency Updates |
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| Bug Fixes |
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Why Was Yahoo! UI Removed and What Does It Mean?
Yahoo! UI (YUI) was removed from Jenkins core because it's outdated and no longer maintained. This removal completes a multi-year effort to modernize Jenkins' frontend infrastructure.
In practice, this means plugin maintainers had to update their plugins to use modern JavaScript frameworks instead of relying on YUI. Most popular plugins have already been updated, but a few with lower installation counts might still need attention. This change results in better performance and more maintainable code for the entire Jenkins ecosystem.
What Windows Installation Changes Should I Know About?
The ability to install Jenkins as a Windows service directly from the running Jenkins UI has been removed. The jCIFS and j-Interop libraries that supported this functionality and Windows agent launch via DCOM have also been removed.
This matters because these methods were outdated and incompatible with modern Windows versions. Instead, you should use the official Windows MSI package for service installation, which provides more reliable and supported installation methods.
What UI and UX Improvements Were Made?
Jenkins 2.504.x introduces several visual and usability enhancements. The interface now uses OKLCH for more perceptually uniform color definitions, improving visual consistency.
Specific improvements include a refreshed Jenkins CLI page, better-looking user avatars, updated copy button animations, and grouped search results in the Command Palette. The experimental Details widget for builds and console output display option provide more flexibility in how you view build information.
What Performance and Reliability Fixes Were Included?
This release addresses several performance and reliability issues. The upgrade to Winstone 8.7 and Jetty 12.0.19 brings various bug fixes and improvements from the underlying web container.
Key fixes include resolving occasional file write failures on Windows servers due to virus scanner interference, proper date display in the History widget for users with custom time zones, and corrected task notifications for the rebuild plugin and similar functionality.
FAQ
Will my existing plugins work after the YUI removal?
Most plugins will work fine as maintainers have been preparing for this change. Only a few plugins with under 800 installs haven't been updated yet. Check the tracking sheet for specific plugin status.
How do I install Jenkins as a Windows service now?
Use the official Windows MSI package instead of the built-in service installation. The MSI provides a more reliable and supported method for Windows service installation.
What should I do if I encounter plugin issues after upgrading?
First update all plugins to their latest versions. If issues persist, check if the plugin was listed as potentially affected by the YUI removal and contact the plugin maintainer.
Are there any breaking changes for pipeline scripts?
No, the changes in 2.504.x primarily affect the UI and underlying libraries. Pipeline functionality remains unchanged and backward compatible.
How do I enable the experimental Console Output on build page feature?
Experimental features are typically enabled through system properties or feature flags. Check the experimental flags documentation for the specific property to enable this functionality.