org.w3c.dom.DOMException: NAMESPACE_ERR: An attempt is made to create or change an object in a way which is incorrect with regard to namespaces.
        at com.sun.org.apache.xerces.internal.dom.CoreDocumentImpl.checkDOMNSErr(CoreDocumentImpl.java:2515)
        at com.sun.org.apache.xerces.internal.dom.AttrNSImpl.setName(AttrNSImpl.java:113)
        at com.sun.org.apache.xerces.internal.dom.AttrNSImpl.<init>(AttrNSImpl.java:74)
        at com.sun.org.apache.xerces.internal.dom.CoreDocumentImpl.createAttributeNS(CoreDocumentImpl.java:2127)
        at com.sun.org.apache.xerces.internal.dom.ElementImpl.setAttributeNS(ElementImpl.java:656)
        at org.openide.xml.XMLUtil.fixupAttrsSingle(XMLUtil.java:526)
        at org.openide.xml.XMLUtil.fixupAttrs(XMLUtil.java:510)
        at org.openide.xml.XMLUtil.validate(XMLUtil.java:493)
        at org.netbeans.modules.ant.freeform.spi.support.Util$2.run(Util.java:357)
        at org.netbeans.modules.ant.freeform.spi.support.Util$2.run(Util.java:353)
        at org.openide.util.Mutex.writeAccess(Mutex.java:394)
        at org.netbeans.modules.ant.freeform.spi.support.Util.putPrimaryConfigurationData(Util.java:353)
        at org.netbeans.modules.java.freeform.JavaProjectGenerator.putSourceFolders(JavaProjectGenerator.java:236)
        at org.netbeans.modules.java.freeform.ui.ProjectModel$2.run(ProjectModel.java:207)
        at org.netbeans.modules.java.freeform.ui.ProjectModel$2.run(ProjectModel.java:204)
        at org.openide.util.Mutex.writeAccess(Mutex.java:394)
        at org.netbeans.modules.java.freeform.ui.ProjectModel.saveProject(ProjectModel.java:204)
        at org.netbeans.modules.java.freeform.ui.SourceFoldersCategoryProvider$1.actionPerformed(SourceFoldersCategoryProvider.java:87)
        at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener.actionPerformed(CustomizerDialog.java:305)
        at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener.access$200(CustomizerDialog.java:221)
        at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener$1.run(CustomizerDialog.java:247)
        at org.openide.util.Mutex.writeAccess(Mutex.java:394)
        at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener.actionPerformed(CustomizerDialog.java:244)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
        at java.awt.Component.processMouseEvent(Component.java:6216)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
        at java.awt.Component.processEvent(Component.java:5981)
        at java.awt.Container.processEvent(Container.java:2041)
        at java.awt.Component.dispatchEventImpl(Component.java:4583)
        at java.awt.Container.dispatchEventImpl(Container.java:2099)
        at java.awt.Component.dispatchEvent(Component.java:4413)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4556)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4220)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4150)
        at java.awt.Container.dispatchEventImpl(Container.java:2085)
        at java.awt.Window.dispatchEventImpl(Window.java:2475)
        at java.awt.Component.dispatchEvent(Component.java:4413)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)