Stack trace appears on the pagewhen when deleting the default build definition of a project group

When deleting the default build definition of a project group
Stack trace appears on the page..

>Show Project Groups link
>Click any Project Group
>Click Build Definitions
> Delete the default build definition of the group.
> Stack trace appears on the page

Error Occurred
org.apache.maven.continuum.ContinuumException: can't remove default build definition from project group

Show/hide Stack Trace

org.apache.maven.continuum.ContinuumException: can't remove default build definition from project group
at org.apache.maven.continuum.core.action.RemoveBuildDefinitionFromProjectGroupAction.execute(RemoveBuildDefinitionFromProjectGroupAction.java:56)
at org.apache.maven.continuum.DefaultContinuum.executeAction(DefaultContinuum.java:2973)
at org.apache.maven.continuum.DefaultContinuum.removeBuildDefinitionFromProjectGroup(DefaultContinuum.java:2391)
at org.apache.maven.continuum.web.action.BuildDefinitionAction.removeFromProjectGroup(BuildDefinitionAction.java:400)
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:585)
at com.opensymphony.xwork.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:358)
at com.opensymphony.xwork.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:218)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:192)
at com.opensymphony.xwork.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:175)
at com.opensymphony.xwork.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:115)
at com.opensymphony.xwork.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at org.apache.maven.continuum.web.interceptor.ForceContinuumConfigurationInterceptor.intercept(ForceContinuumConfigurationInterceptor.java:72)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at org.codehaus.plexus.redback.xwork.interceptor.PolicyEnforcementInterceptor.intercept(PolicyEnforcementInterceptor.java:149)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at org.codehaus.plexus.redback.xwork.interceptor.SecureActionInterceptor.intercept(SecureActionInterceptor.java:178)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at org.codehaus.plexus.xwork.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:58)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:175)
at com.opensymphony.xwork.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:115)
at com.opensymphony.xwork.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:86)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:31)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:31)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:31)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.webwork.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:174)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:31)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.webwork.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:169)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:31)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:151)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:31)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:31)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:31)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:186)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at org.codehaus.plexus.redback.xwork.interceptor.AutoLoginInterceptor.intercept(AutoLoginInterceptor.java:156)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at org.codehaus.plexus.redback.xwork.interceptor.ForceAdminUserInterceptor.intercept(ForceAdminUserInterceptor.java:76)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at org.codehaus.plexus.redback.xwork.interceptor.EnvironmentCheckInterceptor.intercept(EnvironmentCheckInterceptor.java:122)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:190)
at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:116)
at com.opensymphony.webwork.dispatcher.DispatcherUtils.serviceAction(DispatcherUtils.java:273)
at com.opensymphony.webwork.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:202)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1088)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:118)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:52)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1088)
at com.opensymphony.webwork.dispatcher.ActionContextCleanUp.doFilter(ActionContextCleanUp.java:88)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1088)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:729)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:206)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:324)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:829)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:513)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:488)