diff --git a/plugins/calendar/calendar.php b/plugins/calendar/calendar.php
--- a/plugins/calendar/calendar.php
+++ b/plugins/calendar/calendar.php
@@ -788,6 +788,22 @@
       case "subscribe":
         if (!$this->driver->subscribe_calendar($cal))
           $this->rc->output->show_message($this->gettext('errorsaving'), 'error');
+        else {
+          $calendars = $this->driver->list_calendars();
+          $calendar  = $calendars[$cal['id']];
+
+          // find parent folder and check if it's a "user calendar"
+          // if it's also activated we need to refresh it (#5340)
+          while ($calendar['parent']) {
+            if (isset($calendars[$calendar['parent']]))
+              $calendar = $calendars[$calendar['parent']];
+            else
+              break;
+          }
+
+          if ($calendar['id'] != $cal['id'] && $calendar['active'] && $calendar['group'] == "other user")
+            $this->rc->output->command('plugin.refresh_source', $calendar['id']);
+        }
         return;
       case "search":
         $results    = array();
diff --git a/plugins/calendar/calendar_ui.js b/plugins/calendar/calendar_ui.js
--- a/plugins/calendar/calendar_ui.js
+++ b/plugins/calendar/calendar_ui.js
@@ -2958,6 +2958,15 @@
       return false;
     };
 
+    this.calendar_refresh_source = function(id)
+    {
+      // got race-conditions fc.currentFetchID when using refetchEvents,
+      // so we remove and add the source instead
+      // fc.fullCalendar('refetchEvents', me.calendars[id]);
+      fc.fullCalendar('removeEventSource', me.calendars[id]);
+      fc.fullCalendar('addEventSource', me.calendars[id]);
+    };
+
     this.calendar_destroy_source = function(id)
     {
       var delete_ids = [];
@@ -4235,6 +4244,7 @@
   rcmail.register_command('add-resource', function(){ cal.add_resource2event(); }, false);
 
   // register callback commands
+  rcmail.addEventListener('plugin.refresh_source', function(data) { cal.calendar_refresh_source(data); });
   rcmail.addEventListener('plugin.destroy_source', function(p){ cal.calendar_destroy_source(p.id); });
   rcmail.addEventListener('plugin.unlock_saving', function(p){ cal.unlock_saving(); });
   rcmail.addEventListener('plugin.refresh_calendar', function(p){ cal.refresh(p); });
diff --git a/plugins/calendar/drivers/kolab/kolab_user_calendar.php b/plugins/calendar/drivers/kolab/kolab_user_calendar.php
--- a/plugins/calendar/drivers/kolab/kolab_user_calendar.php
+++ b/plugins/calendar/drivers/kolab/kolab_user_calendar.php
@@ -223,11 +223,11 @@
       }
     }
 
-    // aggregate all calendar folders the user shares (but are not subscribed)
-    foreach (kolab_storage::list_user_folders($this->userdata, 'event', false) as $foldername) {
+    // aggregate all calendar folders the user shares (but are not activated)
+    foreach (kolab_storage::list_user_folders($this->userdata, 'event', 2) as $foldername) {
       $cal = new kolab_calendar($foldername, $this->cal);
       foreach ($cal->list_events($start, $end, $search, 1) as $event) {
-        $this->events[$event['id']] = $event;
+        $this->events[$event['id'] ?: $event['uid']] = $event;
         $this->timeindex[$this->time_key($event)] = $event['id'];
       }
     }
diff --git a/plugins/libkolab/lib/kolab_storage.php b/plugins/libkolab/lib/kolab_storage.php
--- a/plugins/libkolab/lib/kolab_storage.php
+++ b/plugins/libkolab/lib/kolab_storage.php
@@ -825,11 +825,7 @@
         if (!$filter) {
             // Get ALL folders list, standard way
             if ($subscribed) {
-                $folders = self::$imap->list_folders_subscribed($root, $mbox);
-                // add temporarily subscribed folders
-                if (self::$with_tempsubs && is_array($_SESSION['kolab_subscribed_folders'])) {
-                    $folders = array_unique(array_merge($folders, $_SESSION['kolab_subscribed_folders']));
-                }
+                $folders = self::_imap_list_subscribed($root, $mbox);
             }
             else {
                 $folders = self::_imap_list_folders($root, $mbox);
@@ -866,12 +862,7 @@
 
         // Get folders list
         if ($subscribed) {
-            $folders = self::$imap->list_folders_subscribed($root, $mbox);
-
-            // add temporarily subscribed folders
-            if (self::$with_tempsubs && is_array($_SESSION['kolab_subscribed_folders'])) {
-                $folders = array_unique(array_merge($folders, $_SESSION['kolab_subscribed_folders']));
-            }
+            $folders = self::_imap_list_subscribed($root, $mbox);
         }
         else {
             $folders = self::_imap_list_folders($root, $mbox);
@@ -934,6 +925,21 @@
         return $folders;
     }
 
+    /**
+     * Wrapper for rcube_imap::list_folders_subscribed()
+     * with support for temporarily subscribed folders
+     */
+    protected static function _imap_list_subscribed($root, $mbox)
+    {
+        $folders = self::$imap->list_folders_subscribed($root, $mbox);
+
+        // add temporarily subscribed folders
+        if (self::$with_tempsubs && is_array($_SESSION['kolab_subscribed_folders'])) {
+            $folders = array_unique(array_merge($folders, $_SESSION['kolab_subscribed_folders']));
+        }
+
+        return $folders;
+    }
 
     /**
      * Search for shared or otherwise not listed groupware folders the user has access
@@ -1538,12 +1544,12 @@
      *
      * @param array   User entry from LDAP
      * @param string  Data type to list folders for (contact,event,task,journal,file,note,mail,configuration)
-     * @param boolean Return subscribed folders only (null to use configured subscription mode)
+     * @param int     1 - subscribed folders only, 0 - all folders, 2 - all non-active
      * @param array   Will be filled with folder-types data
      *
      * @return array List of folders
      */
-    public static function list_user_folders($user, $type, $subscribed = null, &$folderdata = array())
+    public static function list_user_folders($user, $type, $subscribed = 0, &$folderdata = array())
     {
         self::setup();
 
@@ -1554,9 +1560,19 @@
         if (!empty($user[$user_attrib])) {
             list($mbox) = explode('@', $user[$user_attrib]);
 
-            $delimiter = self::$imap->get_hierarchy_delimiter();
-            $other_ns = self::namespace_root('other');
-            $folders = self::list_folders($other_ns . $mbox . $delimiter, '*', $type, $subscribed, $folderdata);
+            $delimiter  = self::$imap->get_hierarchy_delimiter();
+            $other_ns   = self::namespace_root('other');
+            $prefix     = $other_ns . $mbox . $delimiter;
+            $subscribed = (int) $subscribed;
+            $subs       = $subscribed < 2 ? (bool) $subscribed : false;
+            $folders    = self::list_folders($prefix, '*', $type, $subs, $folderdata);
+
+            if ($subscribed === 2 && !empty($folders)) {
+                $active = self::get_states();
+                if (!empty($active)) {
+                    $folders = array_diff($folders, $active);
+                }
+            }
         }
 
         return $folders;