Upgrading to Jenkins LTS 2.492.x

The Yahoo! User Interface library (YUI) is now disabled by default in Jenkins. There have been several pull requests created towards this goal, with work being done over several years by multiple contributors. Additionally, elements of Jenkins that were originally built with YUI have been replaced with alternatives to help ensure there is no loss of functionality.

If you need to re-enable YUI in your Jenkins environment, you must set the following system property:

-Djenkins.model.experimentalflags.RemoveYuiUserExperimentalFlag.defaultValue="false"

Full removal of YUI will occur in a later LTS release, providing time for users to configure their environments accordingly.

The list of agent protocols is no longer configurable through the GUI or the Configuration as Code (JCasC) plugin. Going forward, there are two protocols: one for inbound TCP agents and a ping protocol used to test connectivity. The agentProtocols section of a configuration as code global configuration should be deleted because it will now be ignored. If you do not wish to allow inbound TCP agents, disable the port instead of the protocol.

By default, the Configuration as Code Plugin cancels Jenkins startup when a deprecated section is detected. If the agentProtocols section is in a Jenkins 2.492.1 global configuration, Jenkins 2.492.1 will cancel startup and process no jobs. That is the intentional behavior of the plugin so that administrators detect and apply configuration changes immediately.

The Configuration as Code Plugin can warn when deprecated configuration elements are found instead of canceling startup. Warning on deprecated configuration elements may not handle all configuration changes. If an administrator wants a warning for configuration as code deprecations instead of canceling startup, they can add the following to their configuration as code global configuration: