diff --git a/calendar/inc/class.calendar_so.inc.php b/calendar/inc/class.calendar_so.inc.php
index f72a6ec003..231001b367 100644
--- a/calendar/inc/class.calendar_so.inc.php
+++ b/calendar/inc/class.calendar_so.inc.php
@@ -2149,7 +2149,7 @@ ORDER BY cal_user_type, cal_usre_id
 					'cal_status'	=> $status,
 					'cal_quantity'	=> $quantity,
 					'cal_role'		=> $role,
-					'cal_attendee'  => $type == 'e' ? substr($uid, 1) : null,
+					'cal_user_attendee' => $type == 'e' ? substr($uid, 1) : null,
 				),array(
 					'cal_id'		 => $cal_id,
 					'cal_recur_date' => $start,
diff --git a/calendar/setup/setup.inc.php b/calendar/setup/setup.inc.php
index 515d5252d0..e6d720e063 100755
--- a/calendar/setup/setup.inc.php
+++ b/calendar/setup/setup.inc.php
@@ -10,7 +10,7 @@
  */
 
 $setup_info['calendar']['name']    = 'calendar';
-$setup_info['calendar']['version'] = '14.3.900';
+$setup_info['calendar']['version'] = '14.3.901';
 $setup_info['calendar']['app_order'] = 3;
 $setup_info['calendar']['enable']  = 1;
 $setup_info['calendar']['index']   = 'calendar.calendar_uiviews.index&ajax=true';
diff --git a/calendar/setup/tables_update.inc.php b/calendar/setup/tables_update.inc.php
index 148d616c7b..c7e2c044be 100644
--- a/calendar/setup/tables_update.inc.php
+++ b/calendar/setup/tables_update.inc.php
@@ -2573,7 +2573,7 @@ function calendar_upgrade14_3()
 	// by ordering by status we prever accepted over tentative over unknow over deleted
 	foreach($GLOBALS['egw_setup']->db->select('egw_cal_user', "cal_id,cal_recur_date,$email AS email", array(
 		'cal_user_type' => 'e',
-	), __LINE__, __FILE__, false, "GROUP BY cal_id,cal_recur_date,$email HAVING COUNT(*)>1") as $row)
+	), __LINE__, __FILE__, false, "GROUP BY cal_id,cal_recur_date,$email HAVING COUNT(*)>1", 'calendar') as $row)
 	{
 		$n = 0;
 		foreach($GLOBALS['egw_setup']->db->select('egw_cal_user', "*,$email AS email", array(
@@ -2581,7 +2581,7 @@ function calendar_upgrade14_3()
 			'cal_recur_date' => $row['cal_recur_date'],
 			'cal_user_type' => 'e',
 			$email.'='.$GLOBALS['egw_setup']->db->quote($row['email']),
-		), __LINE__, __FILE__, 'ORDER BY cal_status') as $user)	// order A, T, U, X
+		), __LINE__, __FILE__, false, 'ORDER BY cal_status', 'calendar') as $user)	// order A, T, U, X
 		{
 			if (strpos($user['email'], '@') !== false && !$n++) continue;
 			$GLOBALS['egw_setup']->db->delete('egw_cal_user', array_intersect_key($user, array_flip(array('cal_id','cal_recur_date','cal_user_type','cal_user_id','cal_status'))));
@@ -2606,13 +2606,53 @@ function calendar_upgrade14_3()
 	return $GLOBALS['setup_info']['calendar']['currentver'] = '14.3.001';
 }
 
+/**
+ * Fix NULL in egw_cal_user.cal_user_attendee for recurrences by using value from master (cal_recur_date=0)
+ *
+ * @return string
+ */
+function calendar_upgrade14_3_001()
+{
+	$GLOBALS['calendar_upgrade14_3_001-run'] = true;
+
+	foreach($GLOBALS['egw_setup']->db->query("SELECT egw_cal_user.cal_id AS cal_id,egw_cal_user.cal_user_id AS cal_user_id,egw_cal_user.cal_user_attendee AS cal_user_attendee
+FROM egw_cal_user
+JOIN egw_cal_user user ON user.cal_id=egw_cal_user.cal_id AND user.cal_user_type='e' AND user.cal_user_id=egw_cal_user.cal_user_id AND user.cal_user_attendee IS NULL
+WHERE egw_cal_user.cal_user_type='e' AND egw_cal_user.cal_user_attendee IS NOT NULL
+GROUP BY egw_cal_user.cal_id,egw_cal_user.cal_user_id,egw_cal_user.cal_user_attendee", __LINE__, __FILE__) as $row)
+	{
+		$GLOBALS['egw_setup']->db->update('egw_cal_user', array(
+			'cal_user_attendee' => $row['cal_user_attendee'],
+		), array(
+			'cal_id' => $row['cal_id'],
+			'cal_user_type' => 'e',
+			'cal_user_id' => $row['cal_user_id'],
+			'cal_user_attendee IS NULL'
+		), __LINE__, __FILE__, 'calendar');
+	}
+	return $GLOBALS['setup_info']['calendar']['currentver'] = '14.3.002';
+}
 
 /**
  * Setting new index url from setup.inc.php
  *
  * @return string
  */
-function calendar_upgrade14_3_001()
+function calendar_upgrade14_3_002()
 {
 	return $GLOBALS['setup_info']['calendar']['currentver'] = '14.3.900';
 }
+
+/**
+ * Setting new index url from setup.inc.php
+ *
+ * @return string
+ */
+function calendar_upgrade14_3_900()
+{
+	if (empty($GLOBALS['calendar_upgrade14_3_001-run']))
+	{
+		calendar_upgrade14_3_001();
+	}
+	return $GLOBALS['setup_info']['calendar']['currentver'] = '14.3.901';
+}