Exception in thread "Folder Instance Processor" java.lang.AssertionError: Illegal project.xml
        at org.netbeans.modules.java.j2seproject.SourceRoots.readProjectMetadata(SourceRoots.java:234)
        at org.netbeans.modules.java.j2seproject.SourceRoots.access$200(SourceRoots.java:43)
        at org.netbeans.modules.java.j2seproject.SourceRoots$2.run(SourceRoots.java:104)
        at org.openide.util.Mutex.readAccess(Mutex.java:181)
        at org.netbeans.modules.java.j2seproject.SourceRoots.getRootProperties(SourceRoots.java:100)
        at org.netbeans.modules.java.j2seproject.J2SESources.initSources(J2SESources.java:71)
        at org.netbeans.modules.java.j2seproject.J2SESources.<init>(J2SESources.java:53)
        at org.netbeans.modules.java.j2seproject.J2SEProject.createLookup(J2SEProject.java:138)
        at org.netbeans.modules.java.j2seproject.J2SEProject.<init>(J2SEProject.java:92)
        at org.netbeans.modules.java.j2seproject.J2SEProjectType.createProject(J2SEProjectType.java:41)
        at org.netbeans.modules.project.ant.AntBasedProjectFactorySingleton.loadProject(AntBasedProjectFactorySingleton.java:132)
        at org.netbeans.api.project.ProjectManager.createProject(ProjectManager.java:286)
        at org.netbeans.api.project.ProjectManager.access$700(ProjectManager.java:42)
        at org.netbeans.api.project.ProjectManager$2.run(ProjectManager.java:225)
        at org.openide.util.Mutex.readAccess(Mutex.java:220)
        at org.netbeans.api.project.ProjectManager.findProject(ProjectManager.java:175)
        at org.netbeans.modules.project.ui.OpenProjectList.URLs2Projects(OpenProjectList.java:345)
        at org.netbeans.modules.project.ui.OpenProjectList.loadProjectList(OpenProjectList.java:430)
        at org.netbeans.modules.project.ui.OpenProjectList.getDefault(OpenProjectList.java:97)
        at org.netbeans.modules.project.ui.actions.MainProjectAction.refreshView(MainProjectAction.java:118)
        at org.netbeans.modules.project.ui.actions.MainProjectAction.<init>(MainProjectAction.java:68)
        at org.netbeans.modules.project.ui.actions.MainProjectAction.<init>(MainProjectAction.java:50)
        at org.netbeans.modules.project.ui.actions.Actions.mainProjectSensitiveAction(Actions.java:97)
        at org.netbeans.spi.project.ui.support.MainProjectSensitiveActions.mainProjectSensitiveAction(MainProjectSensitiveActions.java:59)
        at org.netbeans.modules.debugger.projects.MainProjectManager.<init>(MainProjectManager.java:43)
        at org.netbeans.modules.debugger.projects.MainProjectManager.<clinit>(MainProjectManager.java:29)
        at org.netbeans.modules.debugger.projects.StepIntoActionProvider.<init>(StepIntoActionProvider.java:44)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:494)
        at java.lang.Class.newInstance0(Class.java:350)
        at java.lang.Class.newInstance(Class.java:303)
        at org.netbeans.api.debugger.Lookup$MetaInf.createInstance(Lookup.java:247)
        at org.netbeans.api.debugger.Lookup$MetaInf.lookup(Lookup.java:149)
        at org.netbeans.api.debugger.Lookup.lookup(Lookup.java:49)
        at org.netbeans.api.debugger.ActionsManager.initActionImpls(ActionsManager.java:299)
        at org.netbeans.api.debugger.ActionsManager.isEnabled(ActionsManager.java:128)
        at org.netbeans.modules.debugger.ui.actions.DebuggerAction.<init>(DebuggerAction.java:39)
        at org.netbeans.modules.debugger.ui.actions.ContinueAction.<init>(ContinueAction.java:31)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:494)
        at java.lang.Class.newInstance0(Class.java:350)
        at java.lang.Class.newInstance(Class.java:303)
        at org.openide.loaders.InstanceSupport.instanceCreate(InstanceSupport.java:203)
        at org.openide.loaders.InstanceDataObject$Ser.instanceCreate(InstanceDataObject.java:1170)
        at org.openide.loaders.InstanceDataObject.instanceCreate(InstanceDataObject.java:684)
        at org.netbeans.core.ShortcutsFolder.acceptDataObject(ShortcutsFolder.java:128)
        at org.openide.loaders.FolderInstance.defaultProcessObjects(FolderInstance.java:629)
        at org.openide.loaders.FolderInstance.access$000(FolderInstance.java:68)        at org.openide.loaders.FolderInstance$2.run(FolderInstance.java:601)
        at org.openide.util.Task.run(Task.java:189)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:330)        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:721)