diff --git a/.travis.yml b/.travis.yml
index 3a7a2d7378e..6da8aa1681b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -25,8 +25,7 @@ env:
 # Aim to run tests on all versions of php, make sure each db is run at least once
 matrix:
   include:
-    - php: 5.5
-      dist: trusty
+    - php: 5.6
       env: DB="postgresql" DB_USER="postgres"
     - php: 5.6
       env: DB="mysql" DB_USER="root"
diff --git a/kernel/classes/datatypes/ezobjectrelationlist/ezobjectrelationlisttype.php b/kernel/classes/datatypes/ezobjectrelationlist/ezobjectrelationlisttype.php
index 1b0f341611e..97ef51e7902 100644
--- a/kernel/classes/datatypes/ezobjectrelationlist/ezobjectrelationlisttype.php
+++ b/kernel/classes/datatypes/ezobjectrelationlist/ezobjectrelationlisttype.php
@@ -215,7 +215,6 @@ function fetchObjectAttributeHTTPInput( $http, $base, $contentObjectAttribute )
         {
             $content['relation_list'] = array();
             $contentObjectAttribute->setContent( $content );
-            $contentObjectAttribute->store();
             return true;
         }
         // Type is browse and we have no http input
diff --git a/kernel/private/classes/ezcontentobjectstate.php b/kernel/private/classes/ezcontentobjectstate.php
index 27f320aa2fe..1d1f115d53a 100644
--- a/kernel/private/classes/ezcontentobjectstate.php
+++ b/kernel/private/classes/ezcontentobjectstate.php
@@ -67,6 +67,7 @@ static function definition()
      */
     public static function fetchById( $id )
     {
+        $id = (int)$id;
         $states = self::fetchByConditions( array( "ezcobj_state.id=$id" ), 1, 0 );
         $state = count( $states ) > 0 ? $states[0] : false;
         return $state;
@@ -145,6 +146,7 @@ private static function fetchByConditions( $conditions, $limit, $offset )
      */
     public static function fetchByGroup( $groupID, $limit = false, $offset = false )
     {
+        $groupID = (int)$groupID;
         return self::fetchByConditions( array( "ezcobj_state_group.id=$groupID" ), $limit, $offset );
     }
 
diff --git a/kernel/private/classes/ezcontentobjectstategroup.php b/kernel/private/classes/ezcontentobjectstategroup.php
index 8ef56dc738a..008ab006dc7 100644
--- a/kernel/private/classes/ezcontentobjectstategroup.php
+++ b/kernel/private/classes/ezcontentobjectstategroup.php
@@ -65,6 +65,7 @@ public static function definition()
      */
     public static function fetchById( $id )
     {
+        $id = (int)$id;
         $stateGroups = self::fetchByConditions( array( "ezcobj_state_group.id=$id" ), 1, 0 );
         $stateGroup = count( $stateGroups ) > 0 ? $stateGroups[0] : false;
         return $stateGroup;
diff --git a/kernel/shop/discountruleedit.php b/kernel/shop/discountruleedit.php
index b64f252d503..e0ab3145f23 100644
--- a/kernel/shop/discountruleedit.php
+++ b/kernel/shop/discountruleedit.php
@@ -46,9 +46,9 @@
                                                         'discountrule_id' => $discountRuleID ),
                                     'persistent_data' => array( 'discountrule_name' => $http->postVariable( 'discountrule_name' ),
                                                                 'discountrule_percent' => $http->postVariable( 'discountrule_percent' ),
-                                                                'Contentclasses' => ( $http->hasPostVariable( 'Contentclasses' ) )? serialize( $http->postVariable( 'Contentclasses' ) ): '',
-                                                                'Sections' => ( $http->hasPostVariable( 'Sections' ) )? serialize( $http->postVariable( 'Sections' ) ): '',
-                                                                'Products' => ( $http->hasPostVariable( 'Products' ) )? serialize( $http->postVariable( 'Products' ) ): '' ),
+                                                                'Contentclasses' => ( $http->hasPostVariable( 'Contentclasses' ) )? json_encode( $http->postVariable( 'Contentclasses' ) ): '',
+                                                                'Sections' => ( $http->hasPostVariable( 'Sections' ) )? json_encode( $http->postVariable( 'Sections' ) ): '',
+                                                                'Products' => ( $http->hasPostVariable( 'Products' ) )? json_encode( $http->postVariable( 'Products' ) ): '' ),
                                     'from_page' => "/shop/discountruleedit/$discountGroupID/$discountRuleID" ),
                              $module );
     return;
@@ -68,7 +68,7 @@
         $discountRuleSelectedClasses = $http->postVariable( 'Contentclasses' );
         if ( !is_array( $discountRuleSelectedClasses ) )
         {
-            $discountRuleSelectedClasses = unserialize( $discountRuleSelectedClasses );
+            $discountRuleSelectedClasses = json_decode( $discountRuleSelectedClasses );
         }
     }
 
@@ -78,7 +78,7 @@
         $discountRuleSelectedSections = $http->postVariable( 'Sections' );
         if ( !is_array( $discountRuleSelectedSections ) )
         {
-            $discountRuleSelectedSections = unserialize( $discountRuleSelectedSections );
+            $discountRuleSelectedSections = json_decode( $discountRuleSelectedSections );
         }
     }
 
@@ -88,7 +88,7 @@
         $discountRuleSelectedProducts = $http->postVariable( 'Products' );
         if ( !is_array( $discountRuleSelectedProducts ) )
         {
-            $discountRuleSelectedProducts = unserialize( $discountRuleSelectedProducts );
+            $discountRuleSelectedProducts = json_decode( $discountRuleSelectedProducts );
         }
     }
 
diff --git a/lib/ezutils/classes/eztimestamp.php b/lib/ezutils/classes/eztimestamp.php
index fcbecd85b23..6e952f05ffb 100644
--- a/lib/ezutils/classes/eztimestamp.php
+++ b/lib/ezutils/classes/eztimestamp.php
@@ -14,6 +14,12 @@ class eZTimestamp
      \return a timestamp in UTC
     */
     public static function getUtcTimestampFromLocalTimestamp( $localTimestamp ) {
+
+        if ( $localTimestamp === null || $localTimestamp === '' )
+        {
+            return null;
+        }
+
         $utcTimezone = new \DateTimeZone( 'UTC' );
         $localTimezone = new \DateTimeZone( date_default_timezone_get() );
 
@@ -28,6 +34,12 @@ public static function getUtcTimestampFromLocalTimestamp( $localTimestamp ) {
      \return a timestamp in timezone defined in php.ini
     */
     public static function getLocalTimestampFromUtcTimestamp( $utcTimestamp ) {
+
+        if ( $utcTimestamp === null || $utcTimestamp === '' )
+        {
+            return null;
+        }
+
         $utcTimezone = new \DateTimeZone( 'UTC' );
         $localTimezone = new \DateTimeZone( date_default_timezone_get() );
 
diff --git a/settings/contentstructuremenu.ini b/settings/contentstructuremenu.ini
index d763b79d23e..98d0d492126 100644
--- a/settings/contentstructuremenu.ini
+++ b/settings/contentstructuremenu.ini
@@ -36,9 +36,8 @@ MaxNodes=150
 #    SortBy[]
 #    SortBy[]=name/ascending
 #    SortBy[]=published/descending
-# if set to "false" - default sorting will be implemented
-# (which is defined for each node)
-SortBy=false
+# if an empty array, it uses the sorting defined for each node instead (from the Ordering tab)
+SortBy[]
 
 # enabled/disabled
 ToolTips=enabled