Index: _source/plugins/toolbar/plugin.js =================================================================== --- _source/plugins/toolbar/plugin.js (revision 3938) +++ _source/plugins/toolbar/plugin.js (working copy) @@ -127,8 +127,17 @@ for ( var r = 0 ; r < toolbar.length ; r++ ) { - var row = toolbar[ r ], - toolbarId = 'cke_' + CKEDITOR.tools.getNextNumber(), + var row = toolbar[ r ]; + + // It's better to check if the row object is really + // available because it's a common mistake to leave + // an extra comma in the toolbar definition + // settings, which leads on the editor not loading + // at all in IE. (#3983) + if ( !row ) + continue; + + var toolbarId = 'cke_' + CKEDITOR.tools.getNextNumber(), toolbarObj = { id : toolbarId, items : [] }; if ( groupStarted ) Index: CHANGES.html =================================================================== --- CHANGES.html (revision 3938) +++ CHANGES.html (working copy) @@ -153,7 +153,10 @@