java.lang.IllegalStateException: Cannot generate build scripts from a modified project
        at org.netbeans.spi.project.support.ant.GeneratedFilesHelper$2.run(GeneratedFilesHelper.java:579)
        at org.netbeans.spi.project.support.ant.GeneratedFilesHelper$2.run(GeneratedFilesHelper.java:576)
        at org.openide.util.Mutex.readAccess(Mutex.java:327)
        at org.netbeans.spi.project.support.ant.GeneratedFilesHelper.getBuildScriptState(GeneratedFilesHelper.java:576)
        at org.netbeans.modules.java.j2seproject.ui.customizer.J2SEProjectProperties.save(J2SEProjectProperties.java:402)
        at org.netbeans.modules.java.j2seproject.ui.customizer.CustomizerProviderImpl$StoreListener.actionPerformed(CustomizerProviderImpl.java:160)
        at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener$2$1.run(CustomizerDialog.java:277)
        at org.openide.util.Mutex.writeAccess(Mutex.java:394)
        at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener$2.run(CustomizerDialog.java:273)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:573)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1005)