diff --git a/application/controllers/ErrorController.php b/application/controllers/ErrorController.php
index 7d30d62e5..074e2fdc2 100644
--- a/application/controllers/ErrorController.php
+++ b/application/controllers/ErrorController.php
@@ -4,6 +4,7 @@
 
 // namespace Icinga\Application\Controllers;
 
+use Icinga\Logger\Logger;
 use Icinga\Web\Controller\ActionController;
 use Icinga\Application\Icinga;
 
@@ -21,6 +22,10 @@ class ErrorController extends ActionController
     {
         $error      = $this->_getParam('error_handler');
         $exception  = $error->exception;
+
+        Logger::error($exception);
+        Logger::error('Stacktrace: %s', $exception->getTraceAsString());
+
         switch ($error->type) {
             case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_ROUTE:
             case Zend_Controller_Plugin_ErrorHandler::EXCEPTION_NO_CONTROLLER:
diff --git a/library/Icinga/Data/Db/DbQuery.php b/library/Icinga/Data/Db/DbQuery.php
index 605e36af9..a89544be8 100644
--- a/library/Icinga/Data/Db/DbQuery.php
+++ b/library/Icinga/Data/Db/DbQuery.php
@@ -89,6 +89,17 @@ class DbQuery extends SimpleQuery
     public function getSelectQuery()
     {
         $select = $this->dbSelect();
+
+        // Add order fields to select for postgres distinct queries (#6351)
+        if ($this->hasOrder()
+            && $this->getDatasource()->getDbType() === 'pgsql'
+            && $select->getPart(Zend_Db_Select::DISTINCT) === true) {
+            foreach ($this->getOrder() as $fieldAndDirection) {
+                list($alias, $field) = explode('.', $fieldAndDirection[0]);
+                $this->columns[$field] = $fieldAndDirection[0];
+            }
+        }
+
         $select->columns($this->columns);
         $this->applyFilterSql($select);
 
@@ -102,6 +113,7 @@ class DbQuery extends SimpleQuery
                 );
             }
         }
+
         return $select;
     }
 
diff --git a/modules/monitoring/library/Monitoring/Backend/Ido/Query/CommandQuery.php b/modules/monitoring/library/Monitoring/Backend/Ido/Query/CommandQuery.php
index 664cb3576..c730c078e 100644
--- a/modules/monitoring/library/Monitoring/Backend/Ido/Query/CommandQuery.php
+++ b/modules/monitoring/library/Monitoring/Backend/Ido/Query/CommandQuery.php
@@ -51,10 +51,12 @@ class CommandQuery extends IdoQuery
     {
         $this->select->join(
             array('cnc' => $this->prefix . 'contact_notificationcommands'),
-            'cnc.command_object_id = co.object_id'
+            'cnc.command_object_id = co.object_id',
+            array()
         )->join(
             array('con' => $this->prefix . 'contacts'),
-            'con.contact_id = cnc.contact_id'
+            'con.contact_id = cnc.contact_id',
+            array()
         );
     }
 }
\ No newline at end of file
diff --git a/modules/monitoring/library/Monitoring/Backend/Ido/Query/DowntimeQuery.php b/modules/monitoring/library/Monitoring/Backend/Ido/Query/DowntimeQuery.php
index 1f5e17c6c..fe1152076 100644
--- a/modules/monitoring/library/Monitoring/Backend/Ido/Query/DowntimeQuery.php
+++ b/modules/monitoring/library/Monitoring/Backend/Ido/Query/DowntimeQuery.php
@@ -23,8 +23,8 @@ class DowntimeQuery extends IdoQuery
             'downtime_triggered_by_id' => 'sd.triggered_by_id',
             'downtime_scheduled_start' => 'UNIX_TIMESTAMP(sd.scheduled_start_time)',
             'downtime_scheduled_end'   => 'UNIX_TIMESTAMP(sd.scheduled_end_time)',
-            'downtime_start'           => "UNIX_TIMESTAMP(CASE WHEN sd.trigger_time != '0000-00-00 00:00:00' then sd.trigger_time ELSE sd.scheduled_start_time END)",
-            'downtime_end'             => 'CASE WHEN sd.is_fixed THEN UNIX_TIMESTAMP(sd.scheduled_end_time) ELSE UNIX_TIMESTAMP(sd.trigger_time) + sd.duration END',
+            'downtime_start'           => "UNIX_TIMESTAMP(CASE WHEN UNIX_TIMESTAMP(sd.trigger_time) > 0 then sd.trigger_time ELSE sd.scheduled_start_time END)",
+            'downtime_end'             => 'CASE WHEN sd.is_fixed > 0 THEN UNIX_TIMESTAMP(sd.scheduled_end_time) ELSE UNIX_TIMESTAMP(sd.trigger_time) + sd.duration END',
             'downtime_duration'        => 'sd.duration',
             'downtime_is_in_effect'    => 'sd.is_in_effect',
             'downtime_internal_id'     => 'sd.internal_downtime_id',
diff --git a/modules/monitoring/library/Monitoring/Backend/Ido/Query/GroupsummaryQuery.php b/modules/monitoring/library/Monitoring/Backend/Ido/Query/GroupsummaryQuery.php
index 914441d03..3b7fdaa06 100644
--- a/modules/monitoring/library/Monitoring/Backend/Ido/Query/GroupsummaryQuery.php
+++ b/modules/monitoring/library/Monitoring/Backend/Ido/Query/GroupsummaryQuery.php
@@ -4,6 +4,7 @@
 
 namespace Icinga\Module\Monitoring\Backend\Ido\Query;
 
+use Icinga\Logger\Logger;
 use Zend_Db_Select;
 
 class GroupSummaryQuery extends IdoQuery
@@ -69,8 +70,15 @@ class GroupSummaryQuery extends IdoQuery
             )
         );
 
+        $groupColumn = 'hostgroup';
+
+        if (in_array('servicegroup', $this->desiredColumns)) {
+            $groupColumn = 'servicegroup';
+        }
+
         $union = $this->db->select()->union(array($hosts, $services), Zend_Db_Select::SQL_UNION_ALL);
-        $this->select->from(array('statussummary' => $union), '*')->group($columns[0]);
+        $this->select->from(array('statussummary' => $union), array($groupColumn))->group(array($groupColumn));
+
         $this->joinedVirtualTables = array(
             'servicestatussummary'  => true,
             'hoststatussummary'     => true
diff --git a/modules/monitoring/library/Monitoring/Backend/Ido/Query/NotificationhistoryQuery.php b/modules/monitoring/library/Monitoring/Backend/Ido/Query/NotificationhistoryQuery.php
index e557f4c7b..64c7e69b8 100644
--- a/modules/monitoring/library/Monitoring/Backend/Ido/Query/NotificationhistoryQuery.php
+++ b/modules/monitoring/library/Monitoring/Backend/Ido/Query/NotificationhistoryQuery.php
@@ -85,7 +85,8 @@ class NotificationhistoryQuery extends IdoQuery
             $this->select->group('n.object_id')
                 ->group('n.start_time')
                 ->group('n.output')
-                ->group('n.state');
+                ->group('n.state')
+                ->group('o.objecttype_id');
         }
 
         $this->joinedVirtualTables = array('history' => true);
diff --git a/modules/monitoring/library/Monitoring/Backend/Ido/Query/StatusQuery.php b/modules/monitoring/library/Monitoring/Backend/Ido/Query/StatusQuery.php
index 2006228b1..d5da738a0 100644
--- a/modules/monitoring/library/Monitoring/Backend/Ido/Query/StatusQuery.php
+++ b/modules/monitoring/library/Monitoring/Backend/Ido/Query/StatusQuery.php
@@ -487,10 +487,10 @@ class StatusQuery extends IdoQuery
     {
         $sub = '(SELECT'
             . ' lc.object_id,'
-            . " CASE WHEN lc.entry_type = 1 THEN CONCAT('[' || c.author_name || '] ' || c.comment_data) ELSE NULL END AS last_comment_data,"
-            . " CASE WHEN lc.entry_type = 2 THEN CONCAT('[' || c.author_name || '] ' || c.comment_data) ELSE NULL END AS last_downtime_data,"
-            . " CASE WHEN lc.entry_type = 3 THEN CONCAT('[' || c.author_name || '] ' || c.comment_data) ELSE NULL END AS last_flapping_data,"
-            . " CASE WHEN lc.entry_type = 4 THEN CONCAT('[' || c.author_name || '] ' || c.comment_data) ELSE NULL END AS last_ack_data"
+            . " CASE WHEN lc.entry_type = 1 THEN '[' || c.author_name || '] ' || c.comment_data ELSE NULL END AS last_comment_data,"
+            . " CASE WHEN lc.entry_type = 2 THEN '[' || c.author_name || '] ' || c.comment_data ELSE NULL END AS last_downtime_data,"
+            . " CASE WHEN lc.entry_type = 3 THEN '[' || c.author_name || '] ' || c.comment_data ELSE NULL END AS last_flapping_data,"
+            . " CASE WHEN lc.entry_type = 4 THEN '[' || c.author_name || '] ' || c.comment_data ELSE NULL END AS last_ack_data"
             . ' FROM icinga_comments c'
             . ' JOIN (SELECT'
             . ' MAX(comment_id) as comment_id,'
@@ -499,7 +499,8 @@ class StatusQuery extends IdoQuery
 	        . ' FROM icinga_comments'
             . ' WHERE entry_type = 1 OR entry_type = 4'
 	        . ' GROUP BY object_id, entry_type'
-            . ') lc ON lc.comment_id = c.comment_id GROUP BY lc.object_id)';
+            . ') lc ON lc.comment_id = c.comment_id'
+            . ' GROUP BY lc.object_id, lc.entry_type, c.author_name, c.comment_data)';
         return new Zend_Db_Expr($sub);
     }