Issue

I did a couple of plugin updates and restarted from the GUI but Jenkins doesn’t want to start anymore.

Seen on UI after restart:

Error

hudson.util.HudsonFailedToLoad: org.jvnet.hudson.reactor.ReactorException: java.lang.Error: java.lang.reflect.InvocationTargetException
	at hudson.WebAppMain$3.run(WebAppMain.java:237)
Caused by: org.jvnet.hudson.reactor.ReactorException: java.lang.Error: java.lang.reflect.InvocationTargetException
	at org.jvnet.hudson.reactor.Reactor.execute(Reactor.java:269)
	at jenkins.InitReactorRunner.run(InitReactorRunner.java:44)
	at jenkins.model.Jenkins.executeReactor(Jenkins.java:916)
	at jenkins.model.Jenkins.<init>(Jenkins.java:815)
	at hudson.model.Hudson.<init>(Hudson.java:85)
	at hudson.model.Hudson.<init>(Hudson.java:81)
	at hudson.WebAppMain$3.run(WebAppMain.java:225)
Caused by: java.lang.Error: java.lang.reflect.InvocationTargetException
	at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:110)
	at hudson.init.TaskMethodFinder$TaskImpl.run(TaskMethodFinder.java:176)
	at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:282)
	at jenkins.model.Jenkins$7.runTask(Jenkins.java:905)
	at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:210)
	at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:117)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:106)
	... 8 more
Caused by: java.lang.NoClassDefFoundError: org/jenkinsci/plugins/workflow/actions/NotExecutedNodeAction
	at com.cloudbees.workflow.cps.checkpoint.CpsCheckpoint.setFlowNodeStorageXStreamAliases(CpsCheckpoint.java:309)
	... 13 more
Caused by: java.lang.ClassNotFoundException: org.jenkinsci.plugins.workflow.actions.NotExecutedNodeAction
	at jenkins.util.AntClassLoader.findClassInComponents(AntClassLoader.java:1376)
	at jenkins.util.AntClassLoader.findClass(AntClassLoader.java:1326)
	at jenkins.util.AntClassLoader.loadClass(AntClassLoader.java:1079)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
	... 14 more

Environment

Jenkins: 1.625.3.1

Pipeline API Plugin: 1.13

Resolution

First of all, check if the Pipeline plugins are not disabled, so there should be no workflow-*.[hpi|jpi].disabled file into the $JENKINS_HOME/plugins directory. You must remove them in case of.

If not, here the steps that fixed the issue with the environment described above:
1. Download the workflow-api version 1.14 from the Jenkins plugins download site
2. Remove the workflow-api.jpi folder and file from the $JENKINS_HOME/plugins directory
3. Copy the workflow-api.hpi file into the $JENKINS_HOME/plugins directory
4. Create a workflow-api.jpi.pinned empty file into the $JENKINS_HOME/plugins directory

Now, you can start Jenkins.