java.lang.NoClassDefFoundError: Could not initialize class org.netbeans.api.project.ui.OpenProjects
   at org.netbeans.modules.project.ant.ProjectLibraryProvider.getOpenAreas(ProjectLibraryProvider.java:184)
   at org.netbeans.modules.project.libraries.LibraryAccessor.getOpenAreas(LibraryAccessor.java:100)
   at org.netbeans.api.project.libraries.LibraryManager.getOpenManagers(LibraryManager.java:554)
   at org.netbeans.modules.java.j2seplatform.libraries.J2SELibrarySourceForBinaryQuery.preInit(J2SELibrarySourceForBinaryQuery.java:131)
   at org.netbeans.modules.java.j2seplatform.J2SEPlatformWarmUp.preInitJ2SELibsSFBQ(J2SEPlatformWarmUp.java:62)
   at org.netbeans.modules.java.j2seplatform.J2SEPlatformWarmUp.run(J2SEPlatformWarmUp.java:56)
   at org.netbeans.core.startup.WarmUpSupport.run(WarmUpSupport.java:98)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1423)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)