Until very recently, I never had Run Selector installed, and Copy Artifact worked just fine. Today, I updated a bunch of plugins (especially the SCM API 2 stuff) and Jenkins core, and suddenly Copy Artifact failed to initalize with an NPE:

java.lang.NullPointerException
at hudson.plugins.copyartifact.BuildSelectorParameter.initAliases(BuildSelectorParameter.java:156)
at hudson.plugins.copyartifact.CopyArtifactPlugin.postInitialize(CopyArtifactPlugin.java:35)
at hudson.PluginManager$2$1$2.run(PluginManager.java:543)
at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:169)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:282)
at jenkins.model.Jenkins$7.runTask(Jenkins.java:1064)
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)

I initially thought that installing the Run Selector plugin fixed this problem, despite never needing it before and there not being a dependency. However, I have now seen the crash return one time on startup, even with Run Selector installed, and then go away after another restart of Jenkins. So it seems to be nondeterministic and happen during some boots but not others.