java.io.FileNotFoundException: C:\Users\giorgo\AppData\Roaming\NetBeans\8.1\config\Preferences\org\netbeans\modules\uihandler.properties (The requested operation cannot be performed on a file with a user-mapped section open)
   at java.io.FileOutputStream.open0(FileOutputStream.java:0)
   at java.io.FileOutputStream.open(FileOutputStream.java:270)
   at java.io.FileOutputStream.<init>(FileOutputStream.java:213)
   at java.io.FileOutputStream.<init>(FileOutputStream.java:162)
   at org.openide.filesystems.LocalFileSystem.outputStream(LocalFileSystem.java:446)
   at org.openide.filesystems.LocalFileSystem$Impl.outputStream(LocalFileSystem.java:678)
   at org.openide.filesystems.StreamPool.createOutputStream(StreamPool.java:142)
   at org.openide.filesystems.AbstractFileObject.getOutputStream(AbstractFileObject.java:254)
   at org.openide.filesystems.AbstractFileObject.getOutputStream(AbstractFileObject.java:236)
   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:268)
   at org.netbeans.core.startup.preferences.PropertiesStorage.save(PropertiesStorage.java:238)
Caused: java.util.prefs.BackingStoreException: java.io.FileNotFoundException: C:\Users\giorgo\AppData\Roaming\NetBeans\8.1\config\Preferences\org\netbeans\modules\uihandler.properties (The requested operation cannot be performed on a file with a user-mapped section open)
   at org.netbeans.core.startup.preferences.NbPreferences.flushSpi(NbPreferences.java:252)
   at org.netbeans.core.startup.preferences.NbPreferences$1$1.run(NbPreferences.java:86)
   at org.netbeans.core.startup.preferences.PropertiesStorage$3.run(PropertiesStorage.java:355)
   at org.openide.filesystems.EventControl.runAtomicAction(EventControl.java:127)
   at org.openide.filesystems.FileSystem.runAtomicAction(FileSystem.java:519)
   at org.netbeans.core.startup.preferences.PropertiesStorage.runAtomic(PropertiesStorage.java:353)
   at org.netbeans.core.startup.preferences.NbPreferences$1.run(NbPreferences.java:81)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)