[slavik81]

I don't update or install plug-ins without doing a taking a snapshot of the Jenkins machine. A new plug-in version may force various other plug-ins to update, and thereby break the many plug-ins that have incomplete dependency specifications.

I also found that downgrade may not fix the problem, as the upgrade may change your configuration files to use newer features, causing Jenkins to choke on them once downgraded.

Jenkins is a spiderweb of plug-ins held together by shoestring. It's a very useful tool, but extremely fragile.