diff --git a/calendar/js/app.js b/calendar/js/app.js
index b947a85af1..5a9f81e32e 100644
--- a/calendar/js/app.js
+++ b/calendar/js/app.js
@@ -85,7 +85,7 @@ app.classes.calendar = AppJS.extend(
 		this._init_sidebox(sidebox);
 
 		var content = this.et2.getArrayMgr('content');
-		
+
 		switch (_name)
 		{
 			case 'calendar.list':
@@ -101,7 +101,8 @@ app.classes.calendar = AppJS.extend(
 					{
 						this.set_enddate_visibility();
 						this.check_recur_type();
-						this.et2.getWidgetById('recur_exception').set_disabled(typeof content.data['recur_exception'][0] == 'undefined');
+						this.et2.getWidgetById('recur_exception').set_disabled(!content.data.recur_exception ||
+							typeof content.data.recur_exception[0] == 'undefined');
 					}
 					else
 					{
@@ -175,15 +176,15 @@ app.classes.calendar = AppJS.extend(
 					{
 						var iframe = parent.jQuery(parent.document).find('.egw_fw_content_browser_iframe');
 						var calTab = iframe.parentsUntil(jQuery('.egw_fw_ui_tab_content'),'.egw_fw_ui_tab_content');
-						
-						if (!calTab.is(':visible')) 
+
+						if (!calTab.is(':visible'))
 						{
-							// F.F can not handle to style correctly an iframe which is hidden (display:none), therefore we need to 
+							// F.F can not handle to style correctly an iframe which is hidden (display:none), therefore we need to
 							// bind a handler to refresh the calendar views after it shows up
 							iframe.one('show',function(){egw_refresh('','calendar');})
 						}
 						else
-						{	
+						{
 							//window.location.reload();
 							window.egw_refresh('refreshing calendar','calendar');
 						}
@@ -451,7 +452,7 @@ app.classes.calendar = AppJS.extend(
 							{
 								// bind on tooltip close event
 								$ttp.on("tooltipclose", function (event, ui){
-									// bind hover handler on tooltip helper in order to be able to freeze the tooltip and scrolling 
+									// bind hover handler on tooltip helper in order to be able to freeze the tooltip and scrolling
 									ui.tooltip.hover(
 										function () {
 											var $ttp_helper = jQuery(this);