java.lang.Exception
   at org.openide.filesystems.StreamPool$NotifyOutputStream.<init>(StreamPool.java:359)
   at org.openide.filesystems.StreamPool.createOutputStream(StreamPool.java:138)
   at org.openide.filesystems.AbstractFileObject.getOutputStream(AbstractFileObject.java:244)
   at org.openide.filesystems.AbstractFileObject.getOutputStream(AbstractFileObject.java:226)
   at org.openide.filesystems.MultiFileObject.getOutputStream(MultiFileObject.java:685)
   at org.openide.filesystems.MultiFileObject.getOutputStream(MultiFileObject.java:685)
   at org.netbeans.core.startup.preferences.PropertiesStorage.outputStream(PropertiesStorage.java:263)
Caused: org.openide.filesystems.FileAlreadyLockedException: Preferences/org/netbeans/modules/uihandler.properties
   at org.openide.filesystems.StreamPool$2.write(StreamPool.java:153)
   at java.io.FilterOutputStream.write(FilterOutputStream.java:60)
   at java.io.FilterOutputStream.write(FilterOutputStream.java:108)
   at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:202)
   at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:272)
   at sun.nio.cs.StreamEncoder.implFlush(StreamEncoder.java:276)
   at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:122)
   at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:212)
   at java.io.BufferedWriter.flush(BufferedWriter.java:236)
   at org.openide.util.EditableProperties.store(EditableProperties.java:230)
   at org.netbeans.core.startup.preferences.PropertiesStorage.save(PropertiesStorage.java:237)
Caused: java.util.prefs.BackingStoreException: org.openide.filesystems.FileAlreadyLockedException: Preferences/org/netbeans/modules/uihandler.properties
   at org.netbeans.core.startup.preferences.NbPreferences.flushSpi(NbPreferences.java:210)
   at org.netbeans.core.startup.preferences.NbPreferences$1$1.run(NbPreferences.java:77)
   at org.netbeans.core.startup.preferences.PropertiesStorage$3.run(PropertiesStorage.java:329)
   at org.openide.filesystems.EventControl.runAtomicAction(EventControl.java:127)
   at org.openide.filesystems.FileSystem.runAtomicAction(FileSystem.java:566)
   at org.netbeans.core.startup.preferences.PropertiesStorage.runAtomic(PropertiesStorage.java:327)
   at org.netbeans.core.startup.preferences.NbPreferences$1.run(NbPreferences.java:72)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1411)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1991)