After having disabled the disk-usage plugin, the server does not start any more. Here is the stack-trace:
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:914)
at jenkins.model.Jenkins.<init>(Jenkins.java:813)
at hudson.model.Hudson.<init>(Hudson.java:83)
at hudson.model.Hudson.<init>(Hudson.java:79)
at hudson.WebAppMain$3.run(WebAppMain.java:225)
Caused by: java.lang.Error: java.lang.reflect.InvocationTargetException
at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:109)
at hudson.init.TaskMethodFinder$TaskImpl.run(TaskMethodFinder.java:169)
at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:282)
at jenkins.model.Jenkins$7.runTask(Jenkins.java:903)
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:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
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:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:105)
... 8 more
Caused by: java.lang.NoClassDefFoundError: hudson/plugins/disk_usage/DiskUsagePlugin
at jenkins.metrics.impl.diskusage.DiskUsageMetricProviderImpl.getMetricSet(DiskUsageMetricProviderImpl.java:21)
at jenkins.metrics.api.Metrics.afterExtensionsAugmented(Metrics.java:307)
... 13 more
Caused by: java.lang.ClassNotFoundException: hudson.plugins.disk_usage.DiskUsagePlugin
at jenkins.util.AntClassLoader.findClassInComponents(AntClassLoader.java:1375)
at jenkins.util.AntClassLoader.findClass(AntClassLoader.java:1325)
at jenkins.util.AntClassLoader.loadClass(AntClassLoader.java:1078)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 15 more

I attached a log file with the messages that were isssued arund the startu