There were 5 or 6 plugin updates for Jenkins v.1.476 which I have running on a Linux VM. The UI showed progress while updating as usual and I typically have to refresh the screen to see Jenkins reboot. However, this time it never restarted and was unresponsive. After refreshing a few times, it did show an error
Caused by: java.lang.NoClassDefFoundError: hudson/PluginManager$PluginUpdateMonitor at hudson.maven.PluginImpl.init(PluginImpl.java:54)
According to the log the first failure appears while attempting to scout and then load hudson.maven.MavenModuleSet.
I also have Jenkins running on Windows and it is also not rebooting after updating plugins. I can restart it by running it in Java from the command line.
Has anyone seen this error or have any feedback on why it's happening? Thank you.