Issue
After upgrding my CasC managed instance past version 2.483, I can see stack traces like the ones shown below in the logs and the instance will not come up.
SEVERE jenkins.InitReactorRunner$1#onTaskFailed: Failed ConfigurationAsCode.init io.jenkins.plugins.casc.ConfiguratorException: 'agentProtocols' is deprecated at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.BaseConfigurator.configure(BaseConfigurator.java:330) at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.BaseConfigurator.check(BaseConfigurator.java:293) at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCode.lambda$checkWith$9(ConfigurationAsCode.java:834) at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCode.invokeWith(ConfigurationAsCode.java:777) at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCode.checkWith(ConfigurationAsCode.java:834) at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCode.configureWith(ConfigurationAsCode.java:820) at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCode.configureWith(ConfigurationAsCode.java:699) at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCode.configure(ConfigurationAsCode.java:356) at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCode.init(ConfigurationAsCode.java:345) Caused: io.jenkins.plugins.casc.ConfigurationAsCodeBootFailure at PluginClassLoader for configuration-as-code//io.jenkins.plugins.casc.ConfigurationAsCode.init(ConfigurationAsCode.java:347) at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103) Caused: java.lang.reflect.InvocationTargetException at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:118) at java.base/java.lang.reflect.Method.invoke(Method.java:580) at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:109) Caused: java.lang.Error at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:115) at hudson.init.TaskMethodFinder$TaskImpl.run(TaskMethodFinder.java:185) at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:304) at jenkins.model.Jenkins$5.runTask(Jenkins.java:1144) at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:221) at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:120) at jenkins.security.ImpersonatingExecutorService$1.run(ImpersonatingExecutorService.java:68) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) at java.base/java.lang.Thread.run(Thread.java:1583) SEVERE hudson.util.BootFailure#publish: Failed to initialize Jenkins
Resolution
As you can see in the Jenkins® changelog for version 2.483, the ability to configure agent protocols was removed. This has a side effect on instances being managed by CasC, as these instances, when running in versions lower than 2.483 will include the following section in their jenkins.yaml file:
agentProtocols: - "Diagnostic-Ping" - "JNLP4-connect" - "OperationsCenter2" - "Ping"
The existence of this section will prevent the instance from starting if you are running on a version higher than 2.483 for Jenkins® or 2.479.x for CloudBees operations center, Client Master or Managed Master.
Once you remove this section, everything should get back to normal.