java.lang.Exception
   at org.openide.filesystems.StreamPool$NotifyOutputStream.<init>(StreamPool.java:368)
   at org.openide.filesystems.StreamPool.createOutputStream(StreamPool.java:134)
   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:692)
   at org.openide.filesystems.MultiFileObject.getOutputStream(MultiFileObject.java:692)
   at org.netbeans.core.startup.preferences.PropertiesStorage.outputStream(PropertiesStorage.java:265)
Caused: org.openide.filesystems.FileAlreadyLockedException: Preferences/org/netbeans/modules/uihandler.properties
   at org.openide.filesystems.StreamPool$2.write(StreamPool.java:147)
   at java.io.FilterOutputStream.write(FilterOutputStream.java:77)
   at java.io.FilterOutputStream.write(FilterOutputStream.java:125)
   at sun.nio.cs.StreamEncoder.writeBytes(StreamEncoder.java:221)
   at sun.nio.cs.StreamEncoder.implFlushBuffer(StreamEncoder.java:291)
   at sun.nio.cs.StreamEncoder.implFlush(StreamEncoder.java:295)
   at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:141)
   at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:229)
   at java.io.BufferedWriter.flush(BufferedWriter.java:254)
   at org.openide.util.EditableProperties.store(EditableProperties.java:230)
   at org.netbeans.core.startup.preferences.PropertiesStorage.save(PropertiesStorage.java:236)
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:228)
   at org.netbeans.core.startup.preferences.NbPreferences$1$1.run(NbPreferences.java:84)
   at org.netbeans.core.startup.preferences.PropertiesStorage$3.run(PropertiesStorage.java:352)
   at org.openide.filesystems.EventControl.runAtomicAction(EventControl.java:127)
   at org.openide.filesystems.FileSystem.runAtomicAction(FileSystem.java:609)
   at org.netbeans.core.startup.preferences.PropertiesStorage.runAtomic(PropertiesStorage.java:350)
   at org.netbeans.core.startup.preferences.NbPreferences$1.run(NbPreferences.java:79)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1454)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2048)