diff --git a/calendar/inc/class.calendar_ical.inc.php b/calendar/inc/class.calendar_ical.inc.php
index 3c9f0b1948..0d30209d9c 100644
--- a/calendar/inc/class.calendar_ical.inc.php
+++ b/calendar/inc/class.calendar_ical.inc.php
@@ -211,6 +211,7 @@ class calendar_ical extends calendar_boupdate
 			strtoupper($GLOBALS['egw_info']['user']['preferences']['common']['lang']));
 		$vcal->setAttribute('VERSION', $version);
 		$vcal->setAttribute('METHOD', $method);
+		$events_exported = false;
 
 		if (!is_array($events)) $events = array($events);
 
@@ -893,9 +894,10 @@ class calendar_ical extends calendar_boupdate
 				}
 			}
 			$vcal->addComponent($vevent);
+			$events_exported = true;
 		}
 
-		$retval = $vcal->exportvCalendar();
+		$retval = $events_exported ? $vcal->exportvCalendar() : false;
  		if ($this->log)
  		{
  			error_log(__FILE__.'['.__LINE__.'] '.__METHOD__ .
@@ -1070,7 +1072,7 @@ class calendar_ical extends calendar_boupdate
 									if (!isset($event['participants'][$uid]))
 									{
 										// Add it back in
-										$event['participants'][$uid] = $event['participant_types']['r'][substr($uid,1)] = $status;
+										$event['participants'][$uid] = $status;
 									}
 								}
 								break;
@@ -1083,7 +1085,14 @@ class calendar_ical extends calendar_boupdate
 				else
 				{
 					// no merge
-					if (!isset($this->supportedFields['participants']) || !count($event['participants']))
+					if(!isset($this->supportedFields['category']))
+					{
+						$event['category'] = $event_info['stored_event']['category'];
+					}
+					if (!isset($this->supportedFields['participants'])
+						|| !$event['participants']
+						|| !is_array($event['participants'])
+						|| !count($event['participants']))
 					{
 						if ($this->log)
 						{
@@ -1094,7 +1103,6 @@ class calendar_ical extends calendar_boupdate
 						// If this is an updated meeting, and the client doesn't support
 						// participants OR the event no longer contains participants, add them back
 						unset($event['participants']);
-						unset($event['participant_types']);
 					}
 					else
 					{
@@ -1119,20 +1127,19 @@ class calendar_ical extends calendar_boupdate
 								}
 							}
 						}
-					}
-
-					foreach ($event_info['stored_event']['participants'] as $uid => $status)
-					{
-						// Is it a resource and no longer present in the event?
-						if ($uid[0] == 'r' && !isset($event['participants'][$uid]))
+						foreach ($event_info['stored_event']['participants'] as $uid => $status)
 						{
-							if ($this->log)
+							// Is it a resource and no longer present in the event?
+							if ($uid[0] == 'r' && !isset($event['participants'][$uid]))
 							{
-								error_log(__FILE__.'['.__LINE__.'] '.__METHOD__.
-									"() Restore resource $uid to status $status\n",3,$this->logfile);
+								if ($this->log)
+								{
+									error_log(__FILE__.'['.__LINE__.'] '.__METHOD__.
+										"() Restore resource $uid to status $status\n",3,$this->logfile);
+								}
+								// Add it back in
+								$event['participants'][$uid] = $status;
 							}
-							// Add it back in
-							$event['participants'][$uid] = $event['participant_types']['r'][substr($uid,1)] = $status;
 						}
 					}
 
@@ -1188,7 +1195,9 @@ class calendar_ical extends calendar_boupdate
 					$event['owner'] = $this->user;
 				}
 
-				if (!is_array($event['participants']) || !count($event['participants']))
+				if (!$event['participants']
+					|| !is_array($event['participants'])
+					|| !count($event['participants']))
 				{
 					$status = $event['owner'] == $this->user ? 'A' : 'U';
 					$status = calendar_so::combine_status($status, 1, 'CHAIR');
@@ -1198,7 +1207,7 @@ class calendar_ical extends calendar_boupdate
 				{
 					foreach ($event['participants'] as $uid => $status)
 					{
-						// Is it a resource and no longer present in the event?
+						// if the client did not give us a proper status => set default
 						if ($status[0] == 'X')
 						{
 							if ($uid == $event['owner'])
@@ -1499,46 +1508,49 @@ class calendar_ical extends calendar_boupdate
 				$event_info['stored_event'] = $this->read($updated_id, 0, false, 'server');
 			}
 
-			// update status depending on the given event type
-			switch ($event_info['type'])
+			if (isset($event['participants']))
 			{
-				case 'SINGLE':
-				case 'SERIES-MASTER':
-				case 'SERIES-EXCEPTION':
-				case 'SERIES-EXCEPTION-PROPAGATE':
-					if (is_array($event_info['stored_event'])) // status update requires a stored event
-					{
-						if ($event_info['acl_edit'])
+				// update status depending on the given event type
+				switch ($event_info['type'])
+				{
+					case 'SINGLE':
+					case 'SERIES-MASTER':
+					case 'SERIES-EXCEPTION':
+					case 'SERIES-EXCEPTION-PROPAGATE':
+						if (is_array($event_info['stored_event'])) // status update requires a stored event
 						{
-							// update all participants if we have the right to do that
-							$this->update_status($event, $event_info['stored_event']);
+							if ($event_info['acl_edit'])
+							{
+								// update all participants if we have the right to do that
+								$this->update_status($event, $event_info['stored_event']);
+							}
+							elseif (isset($event['participants'][$this->user]) || isset($event_info['stored_event']['participants'][$this->user]))
+							{
+								// update the users status only
+								$this->set_status($event_info['stored_event']['id'], $this->user,
+									($event['participants'][$this->user] ? $event['participants'][$this->user] : 'R'), 0, true);
+							}
 						}
-						elseif (isset($event['participants'][$this->user]) || isset($event_info['stored_event']['participants'][$this->user]))
-						{
-							// update the users status only
-							$this->set_status($event_info['stored_event']['id'], $this->user,
-								($event['participants'][$this->user] ? $event['participants'][$this->user] : 'R'), 0, true);
-						}
-					}
-					break;
+						break;
 
-				case 'SERIES-PSEUDO-EXCEPTION':
-					if (is_array($event_info['master_event'])) // status update requires a stored master event
-					{
-						$recurrence = $this->date2usertime($event['recurrence']);
-						if ($event_info['acl_edit'])
+					case 'SERIES-PSEUDO-EXCEPTION':
+						if (is_array($event_info['master_event'])) // status update requires a stored master event
 						{
-							// update all participants if we have the right to do that
-							$this->update_status($event, $event_info['stored_event'], $recurrence);
+							$recurrence = $this->date2usertime($event['recurrence']);
+							if ($event_info['acl_edit'])
+							{
+								// update all participants if we have the right to do that
+								$this->update_status($event, $event_info['stored_event'], $recurrence);
+							}
+							elseif (isset($event['participants'][$this->user]) || isset($event_info['master_event']['participants'][$this->user]))
+							{
+								// update the users status only
+								$this->set_status($event_info['master_event']['id'], $this->user,
+									($event['participants'][$this->user] ? $event['participants'][$this->user] : 'R'), $recurrence, true);
+							}
 						}
-						elseif (isset($event['participants'][$this->user]) || isset($event_info['master_event']['participants'][$this->user]))
-						{
-							// update the users status only
-							$this->set_status($event_info['master_event']['id'], $this->user,
-								($event['participants'][$this->user] ? $event['participants'][$this->user] : 'R'), $recurrence, true);
-						}
-					}
-					break;
+						break;
+				}
 			}
 
 			// choose which id to return to the client
@@ -1864,6 +1876,7 @@ class calendar_ical extends calendar_boupdate
 					case 'd750i':
 					case 'p910i':
 					case 'g705i':
+					case 'w890i':
 						$this->supportedFields = $defaultFields['basic'];
 						break;
 					default:
@@ -2491,7 +2504,7 @@ class calendar_ical extends calendar_boupdate
 								{
 									//Horde::logMessage("vevent2egw: set status to " . $status,
 									//		__FILE__, __LINE__, PEAR_LOG_DEBUG);
-									$event['participants'][$this->user] =
+									$vcardData['participants'][$this->user] =
 										calendar_so::combine_status($status);
 								}
 								$status = 'U'; // keep the group
@@ -2532,12 +2545,12 @@ class calendar_ical extends calendar_boupdate
 							{
 								$attributes['params']['ROLE'] = 'CHAIR';
 							}
-							if (!isset($event['participants'][$uid]) ||
-									$event['participants'][$uid][0] != 'A')
+							if (!isset($vcardData['participants'][$uid]) ||
+									$vcardData['participants'][$uid][0] != 'A')
 							{
 								// for multiple entries the ACCEPT wins
 								// add quantity and role
-								$event['participants'][$uid] =
+								$vcardData['participants'][$uid] =
 									calendar_so::combine_status($status,
 										$attributes['params']['X-EGROUPWARE-QUANTITY'],
 										$attributes['params']['ROLE']);
@@ -2545,11 +2558,11 @@ class calendar_ical extends calendar_boupdate
 							break;
 
 						case 'ORGANIZER':
-							if (isset($event['participants'][$uid]))
+							if (isset($vcardData['participants'][$uid]))
 							{
-								$status = $event['participants'][$uid];
+								$status = $vcardData['participants'][$uid];
 								calendar_so::split_status($status, $quantity, $role);
-								$event['participants'][$uid] =
+								$vcardData['participants'][$uid] =
 									calendar_so::combine_status($status, $quantity, 'CHAIR');
 							}
 							if (is_numeric($uid) && ($uid == $this->calendarOwner || !$this->calendarOwner))
@@ -2561,10 +2574,10 @@ class calendar_ical extends calendar_boupdate
 							{
 								// we must insert a CHAIR participant to keep the ORGANIZER
 								$event['owner'] = $this->user;
-								if (!isset($event['participants'][$uid]))
+								if (!isset($vcardData['participants'][$uid]))
 								{
 									// save the ORGANIZER as event CHAIR
-									$event['participants'][$uid] =
+									$vcardData['participants'][$uid] =
 										calendar_so::combine_status('U', 1, 'CHAIR');
 								}
 							}
@@ -2781,6 +2794,8 @@ class calendar_ical extends calendar_boupdate
 	 */
 	function update_status($new_event, $old_event , $recur_date=0)
 	{
+		if (!isset($new_event['participants'])) return;
+
 		// check the old list against the new list
 		foreach ($old_event['participants'] as $userid => $status)
   		{
diff --git a/calendar/inc/class.calendar_sif.inc.php b/calendar/inc/class.calendar_sif.inc.php
index f75ffd2a6e..12f45b2b7a 100644
--- a/calendar/inc/class.calendar_sif.inc.php
+++ b/calendar/inc/class.calendar_sif.inc.php
@@ -477,7 +477,7 @@ class calendar_sif extends calendar_boupdate
 				// overwrite with server data for merge
 				foreach ($event_info['stored_event'] as $key => $value)
 				{
-					if (in_array($key, array('participants', 'participant_types')))
+					if ($key == 'participants')
 					{
 						unset($event[$key]);
 						continue;
@@ -490,7 +490,6 @@ class calendar_sif extends calendar_boupdate
 				// not merge
 				// SIF clients do not support participants => add them back
 				unset($event['participants']);
-				unset($event['participant_types']);
 				if ($event['whole_day'] && $event['tzid'] != $event_info['stored_event']['tzid'])
 				{
 					if (!isset(self::$tz_cache[$event_info['stored_event']['tzid']]))
diff --git a/calendar/inc/class.calendar_uiforms.inc.php b/calendar/inc/class.calendar_uiforms.inc.php
index 3514e2204e..3086131594 100644
--- a/calendar/inc/class.calendar_uiforms.inc.php
+++ b/calendar/inc/class.calendar_uiforms.inc.php
@@ -238,7 +238,7 @@ class calendar_uiforms extends calendar_ui
 				$event['end']['hour'] = 23; $event['end']['minute'] = $event['end']['second'] = 59; unset($event['end']['raw']);
 				$event['end'] = $this->bo->date2ts($event['end']);
 			}
-			// some checks for recurances, if you give a date, make it a weekly repeating event and visa versa
+			// some checks for recurrences, if you give a date, make it a weekly repeating event and visa versa
 			if ($event['recur_type'] == MCAL_RECUR_NONE && $event['recur_data']) $event['recur_type'] = MCAL_RECUR_WEEKLY;
 			if ($event['recur_type'] == MCAL_RECUR_WEEKLY && !$event['recur_data'])
 			{
@@ -833,14 +833,11 @@ class calendar_uiforms extends calendar_ui
 					// check if we should create an exception
 					if ($_GET['exception'])
 					{
-						// exception: preserv participants of this event and merge it with the 0-recurrence
-						$participants = array('participants' => $event['participants'],'participant_types' => $event['participant_types']);
-						$event = array_merge($this->bo->read($cal_id,0,true),$participants);
 						$msg = $this->_create_exception($event,$preserv);
 					}
 					else
 					{
-						$event = $this->bo->read($cal_id,0,true); // read the 0-recurrence
+						$event = $this->bo->read($cal_id,0,true);
 					}
 				}
 			}
@@ -1077,12 +1074,12 @@ class calendar_uiforms extends calendar_ui
 			$GLOBALS['egw']->js->set_onload("set_style_by_class('table','end_hide','display','".($content['duration'] && isset($sel_options['duration'][$content['duration']]) ? 'none' : 'block')."');");
 
 			$readonlys['recur_exception'] = !count($content['recur_exception']);	// otherwise we get a delete button
-			
+
 			if ($event['recur_type'] != MCAL_RECUR_NONE)
 			{
 				$onclick =& $etpl->get_cell_attribute('button[delete]','onclick');
 				$onclick = str_replace('Delete this event','Delete this series of recuring events',$onclick);
-				
+
 				// some fundamental values of an existing series should not be changed by the user
 				$readonlys['start'] = $readonlys['whole_day'] = true;
 				$readonlys['recur_type'] = $readonlys['recur_data'] = true;
@@ -1746,7 +1743,7 @@ class calendar_uiforms extends calendar_ui
 				'owner'         =>      'select-account',
 				'cat_id'        =>      'select-cat',
 				'non_blocking'	=>	array(''=>lang('No'), 1=>lang('Yes')),
-		
+
 				'start'		=>	'date-time',
 				'end'		=>	'date-time',
 
@@ -1770,11 +1767,11 @@ class calendar_uiforms extends calendar_ui
 		if($content['recur_type'] || $content['recurrence']) {
 			$content['history']['filter'] = array(
 				'(history_status NOT LIKE \'participants%\' OR (history_status LIKE \'participants%\' AND (
-					history_new_value LIKE \'%' . bo_tracking::ONE2N_SEPERATOR . $content['recurrence'] . '\' OR 
+					history_new_value LIKE \'%' . bo_tracking::ONE2N_SEPERATOR . $content['recurrence'] . '\' OR
 					history_old_value LIKE \'%' . bo_tracking::ONE2N_SEPERATOR . $content['recurrence'] . '\')))'
 			);
 		}
-		
+
 		// Translate labels
 		$tracking = new calendar_tracking();
 		foreach($tracking->field2label as $field => $label) {