I've hit this exception a couple times now... I'm just trying to open Gradle projects. Note that the Open Project... dialog takes a very long time to appear, unacceptably long - tens of seconds.
java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because "value" is null at org.netbeans.core.startup.preferences.NbPreferences.put(NbPreferences.java:154) at org.netbeans.core.startup.preferences.NbPreferences.put(NbPreferences.java:149) at org.netbeans.modules.project.ui.OpenProjectListSettings.setStringList(OpenProjectListSettings.java:169) at org.netbeans.modules.project.ui.OpenProjectListSettings.setOpenProjectsDisplayNames(OpenProjectListSettings.java:219) at org.netbeans.modules.project.ui.OpenProjectList.saveProjectList(OpenProjectList.java:1462) at org.netbeans.modules.project.ui.OpenProjectList.access$2300(OpenProjectList.java:116) at org.netbeans.modules.project.ui.OpenProjectList$10.run(OpenProjectList.java:873) at org.netbeans.modules.project.ui.OpenProjectList$10.run(OpenProjectList.java:870) at org.netbeans.modules.openide.util.DefaultMutexImplementation.writeAccess(DefaultMutexImplementation.java:229) at org.openide.util.Mutex.writeAccess(Mutex.java:252) at org.netbeans.modules.project.ui.OpenProjectList.open(OpenProjectList.java:870) at org.netbeans.modules.project.ui.OpenProjectList$6.run(OpenProjectList.java:672) at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1418) at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:45) at org.openide.util.lookup.Lookups.executeWith(Lookups.java:278) [catch] at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)
