I tried to install the crowd 2 plugin as per instructions, here: https://stackoverflow.com/questions/15411208/authenticate-jenkins-users-against-jira

I downloaded the plugin through the available tab in the plugins page.

This resulted in exception as described here: https://issues.jenkins-ci.org/browse/JENKINS-59301 

Before I could resolve this, the jenkins install was updated to 2.204.4. When I tried to login after the update, the exception occurred immedialetly after login. See the attached file for the stack-trace that is displayed.

Now I cannot do anything at all in jenkins. I suppose uninstalling the crowd 2 plugin could solve this for now, but I have no idea how since the jenkins admin page is inaccessible.