I installed CI game plugin 1.6 on Hudson 1.233 and tried to enable the ci game on an existing freeform project.
When pressing submit on the configure job page, I get the following error message (embedded in a hudson-style
page, not a tomcat error page):

Failed to parse form data. Please report this probelm as a bug JSON=

{"publisher0": {"latestOnly":false,"excludes":"","artifacts":"trunk/xxx/target/xxx.jar,trunk/xxx/target/ xxx.zip"}

,"publisher3":

{"junitreport_includes":"**/target/surefire-reports/*.xml"}

,"builder":

{"shell":"cd trunk; mvn -fae -Djava.awt.headless=true clean install site","kind":"hudson.tasks.Shell$DescriptorImpl"}

,"wrapper0":

{"timeoutMinutes":"20"}

,"publisher5":

{"childProjects":"xxx","evenIfUnstable":false}

,"publisher7":

{"height":"100","healthy":"0","unHealthy":"10","threshold":""}

,"publisher8":

{"excludePattern":"","height":"100","pattern":"","normal":"TODO, FIXME","healthy":"","high":"","low":"","unHealthy":"","threshold":""}

,"publisher9":

{"height":"100","pattern":"**/findbugsXml.xml","healthy":"","unHealthy":"","threshold":"600"}

,"publisher11":
{},"logrotate":

{"logrotate_nums":"20","logrotate_days":""}

,"publisher10":

{"mailer_recipients":"xxx@xxx.de","mailer_notifyEveryUnstableBuild":true,"mailer_sendToIndividuals":false}

,"description":"","name":"iDLM_trunk_maven","disable":false,"jdk":"jdk1.5.0_14","scm":
{"":"3","svn_use_update":true,"value":"2","browser":

{"stapler- class":"hudson.scm.browsers.Sventon","repositoryInstance":"xxx","url":"http://xxx:8080/sventon/"}

,"loc":

{"location_local":"trunk","location_remote":"svn+ssh://xxx"}

}} net.sf.json.JSONException: null object at
net.sf.json.JSONObject.verifyIsNull(JSONObject.java:2498) at net.sf.json.JSONObject.has
(JSONObject.java:1857) at org.kohsuke.stapler.RequestImpl.bindJSON(RequestImpl.java:293) at
hudson.plugins.mantis.MantisProjectProperty$DescriptorImpl.newInstance(MantisProjectProperty.java:94) at
hudson.model.Job.doConfigSubmit(Job.java:824) at hudson.model.AbstractProject.doConfigSubmit
(AbstractProject.java:312) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at
java.lang.reflect.Method.invoke(Method.java:597) at org.kohsuke.stapler.Function$InstanceFunction.invoke
(Function.java:103) at org.kohsuke.stapler.Function.bindAndinvoke(Function.java:57) at
org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:75) at
org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30) at
org.kohsuke.stapler.Stapler.invoke(Stapler.java:440) at org.kohsuke.stapler.MetaClass$9.doDispatch
(MetaClass.java:263) at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:30) at
org.kohsuke.stapler.Stapler.invoke(Stapler.java:440) at org.kohsuke.stapler.Stapler.invoke(Stapler.java:361) at
org.kohsuke.stapler.Stapler.service(Stapler.java:121) at javax.servlet.http.HttpServlet.service
(HttpServlet.java:803) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter
(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter
(ApplicationFilterChain.java:206) at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:38) at
hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:30) at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at
hudson.security.HudsonFilter.doFilter(HudsonFilter.java:88) at
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) at
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) at
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433) at
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286) at
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844) at
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run
(Thread.java:619)