Unable to open SQL worksheet - oracle-sqldeveloper

Question

This is the error I am getting while opening the SQL workbench.
java.lang.ClassCastException: oracle.javatools.editor.language.plsql.PLSQLLanguageSupport cannot be cast to oracle.dbtools.raptor.plsql.language.PLSQLLanguageSupport
at oracle.dbtools.raptor.plsql.folding.PlSqlFoldingModel.<init>(PlSqlFoldingModel.java:60)
at oracle.dbtools.worksheet.folding.WorksheetFoldingPlugin.createModel(WorksheetFoldingPlugin.java:51)
at oracle.javatools.editor.folding.CodeFoldingMargin.createCodeFoldingModel(CodeFoldingMargin.java:418)
at oracle.javatools.editor.folding.CodeFoldingMargin.attach(CodeFoldingMargin.java:359)
at oracle.javatools.editor.folding.AbstractCodeFoldingPlugin.attach(AbstractCodeFoldingPlugin.java:124)
at oracle.javatools.editor.folding.AbstractCodeFoldingPlugin.installImpl(AbstractCodeFoldingPlugin.java:42)
at oracle.dbtools.worksheet.folding.WorksheetFoldingPlugin.installImpl(WorksheetFoldingPlugin.java:42)
at oracle.javatools.editor.plugins.AbstractEditorPlugin.install(AbstractEditorPlugin.java:43)
at oracle.javatools.editor.BasicEditorPane.installPlugin(BasicEditorPane.java:2722)
at oracle.dbtools.worksheet.editor.WorksheetGUI.<init>(WorksheetGUI.java:862)
at oracle.dbtools.worksheet.editor.Worksheet.createGUI(Worksheet.java:1120)
at oracle.dbtools.worksheet.editor.Worksheet.getWorksheetGUI(Worksheet.java:1494)
at oracle.dbtools.worksheet.editor.Worksheet.getGUI(Worksheet.java:1293)
at com.oracle.jdeveloper.nbwindowsystem.editor.SplitPane.attachEditor(SplitPane.java:1118)
at com.oracle.jdeveloper.nbwindowsystem.editor.SplitPane.attachNewEditor(SplitPane.java:1112)
at com.oracle.jdeveloper.nbwindowsystem.editor.SplitPane.doLayout(SplitPane.java:585)
at com.oracle.jdeveloper.nbwindowsystem.NbEditorManager.whenCurrentEditorChanges(NbEditorManager.java:1637)
at com.oracle.jdeveloper.nbwindowsystem.editor.TabGroup.whenCurrentEditorChanges(TabGroup.java:1026)
at com.oracle.jdeveloper.nbwindowsystem.editor.TabGroup.setCurrentTabGroupState(TabGroup.java:847)
at com.oracle.jdeveloper.nbwindowsystem.editor.TabGroup.addTabGroupState(TabGroup.java:129)
at com.oracle.jdeveloper.nbwindowsystem.NbEditorManager.createEditor(NbEditorManager.java:556)
at com.oracle.jdeveloper.nbwindowsystem.NbEditorManager.createEditor(NbEditorManager.java:533)
at com.oracle.jdeveloper.nbwindowsystem.NbEditorManager.openEditor(NbEditorManager.java:401)
at oracle.ide.cmd.OpenCommand.openWithNoProject(OpenCommand.java:336)
at oracle.ide.cmd.OpenCommand.access$100(OpenCommand.java:63)
at oracle.ide.cmd.OpenCommand$1.run(OpenCommand.java:268)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at oracle.javatools.internal.ui.EventQueueWrapper._dispatchEvent(EventQueueWrapper.java:169)
at oracle.javatools.internal.ui.EventQueueWrapper.dispatchEvent(EventQueueWrapper.java:151)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
Can anyone help me to sort this problem?