The first time you can configure Cobertura for a Job without a problem.

But When you want to build the Job you get this exception:
[INFO] ------------------------------------------------------------------------
[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] null
[INFO] ------------------------------------------------------------------------
[INFO] Trace
java.lang.NullPointerException
at hudson.plugins.cobertura.CoberturaProjectAction.<init>
(CoberturaProjectAction.java:27)
at hudson.plugins.cobertura.MavenCoberturaPublisher.getProjectAction
(MavenCoberturaPublisher.java:198)
at hudson.maven.MavenModule.addTransientActionsFromBuild
(MavenModule.java:373)
at hudson.maven.MavenModule.addTransientActionsFromBuild
(MavenModule.java:45)
at hudson.maven.AbstractMavenProject.updateTransientActions
(AbstractMavenProject.java:33)
at hudson.maven.MavenModuleSet.updateTransientActions
(MavenModuleSet.java:156)
at hudson.maven.MavenModuleSetBuild.notifyModuleBuild
(MavenModuleSetBuild.java:258)
at hudson.maven.MavenBuild$ProxyImpl2.end(MavenBuild.java:357)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.perform
(RemoteInvocationHandler.java:240)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.call
(RemoteInvocationHandler.java:223)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.call
(RemoteInvocationHandler.java:183)
at hudson.remoting.UserRequest.perform(UserRequest.java:69)
at hudson.remoting.UserRequest.perform(UserRequest.java:23)
at hudson.remoting.Request$2.run(Request.java:213)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown
Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
[INFO] ------------------------------------------------------------------------

After that you every action on the Job configuration screen is followed by:
Status Code: 500
Exception:
Stacktrace:
java.lang.NullPointerException
at hudson.plugins.cobertura.CoberturaProjectAction.
(CoberturaProjectAction.java:27)
at hudson.plugins.cobertura.MavenCoberturaPublisher.getProjectAction
(MavenCoberturaPublisher.java:198)
at hudson.maven.MavenModule.addTransientActionsFromBuild
(MavenModule.java:373)
at hudson.maven.MavenModule.addTransientActionsFromBuild
(MavenModule.java:45)
at hudson.maven.AbstractMavenProject.updateTransientActions
(AbstractMavenProject.java:33)
at hudson.maven.MavenModuleSet.updateTransientActions
(MavenModuleSet.java:156)
at hudson.model.AbstractProject.submit(AbstractProject.java:1023)
at hudson.maven.MavenModuleSet.submit(MavenModuleSet.java:541)
at hudson.model.Job.doConfigSubmit(Job.java:858)
at hudson.model.AbstractProject.doConfigSubmit(AbstractProject.java:336)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.kohsuke.stapler.Function$InstanceFunction.invoke
(Function.java:156)
at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:76)
at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:73)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch
(NameBasedDispatcher.java:30)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:438)
at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:181)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch
(NameBasedDispatcher.java:30)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:438)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:356)
at org.kohsuke.stapler.Stapler.service(Stapler.java:116)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:45)
at winstone.ServletConfiguration.execute(ServletConfiguration.java:249)
at winstone.RequestDispatcher.forward(RequestDispatcher.java:335)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:378)
at hudson.util.PluginServletFilter$1.doFilter
(PluginServletFilter.java:68)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:60)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.security.ChainedServletFilter$1.doFilter
(ChainedServletFilter.java:52)
at hudson.security.ChainedServletFilter.doFilter
(ChainedServletFilter.java:44)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:110)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at winstone.RequestDispatcher.forward(RequestDispatcher.java:333)
at winstone.RequestHandlerThread.processRequest
(RequestHandlerThread.java:244)
at winstone.RequestHandlerThread.run(RequestHandlerThread.java:150)
at java.lang.Thread.run(Unknown Source)