If you have historical builds without cobertura then the coburtura graph on the dashboard is broken because of NullPointerException when getting previous result. I deleted the builds that were done before adding coburtura and the error went away. INFO | jvm 1 | 2009/04/02 20:38:20 | 2009-04-02 20:38:20.014::WARN: /hudson/job/connectfour/cobertura/graph INFO | jvm 1 | 2009/04/02 20:38:20 | java.lang.NullPointerException INFO | jvm 1 | 2009/04/02 20:38:20 | at hudson.plugins.cobertura.CoberturaBuildAction.getPreviousResult(CoberturaBuildAction.java:140) INFO | jvm 1 | 2009/04/02 20:38:20 | at hudson.plugins.cobertura.CoberturaBuildAction.getPreviousResult(CoberturaBuildAction.java:125) INFO | jvm 1 | 2009/04/02 20:38:20 | at hudson.plugins.cobertura.CoberturaBuildAction.doGraph(CoberturaBuildAction.java:218) INFO | jvm 1 | 2009/04/02 20:38:20 | at hudson.plugins.cobertura.CoberturaProjectAction.doGraph(CoberturaProjectAction.java:91) INFO | jvm 1 | 2009/04/02 20:38:20 | at sun.reflect.GeneratedMethodAccessor465.invoke(Unknown Source) INFO | jvm 1 | 2009/04/02 20:38:20 | at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) INFO | jvm 1 | 2009/04/02 20:38:20 | at java.lang.reflect.Method.invoke(Method.java:585) INFO | jvm 1 | 2009/04/02 20:38:20 | at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:156) INFO | jvm 1 | 2009/04/02 20:38:20 | at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:76) INFO | jvm 1 | 2009/04/02 20:38:20 | at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:73) INFO | jvm 1 | 2009/04/02 20:38:20 | at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30) INFO | jvm 1 | 2009/04/02 20:38:20 | at org.kohsuke.stapler.Stapler.invoke(Stapler.java:436)