diff --git a/composer.json b/composer.json
index 25546d2..e612d8b 100644
--- a/composer.json
+++ b/composer.json
@@ -1,28 +1,28 @@
 {
 	"name": "kolab/irony",
 	"description": "iRony - The Kolab WebDAV/CalDAV/CardDAV Server",
 	"license": "AGPL-3.0",
 	"version": "0.4-dev",
 	"repositories": [
 		{
 			"type": "pear",
 			"url": "http://pear.php.net/"
 		},
 		{
 			"type": "vcs",
 			"url": "git://git.kolab.org/git/pear/Net_LDAP3"
 		}
 	],
 	"require": {
 		"php": ">=5.4.1",
-		"sabre/dav" : "~2.1.0"
+		"sabre/dav" : "2.1.*"
 	},
 	"require-dev": {
 		"pear/mail_mime": ">=1.8.9",
-		"pear/mail_mime-decode": ">=1.5.5",
+		"pear/mail_mime-decode": "~1.5.5",
 		"pear-pear.php.net/net_idna2": ">=0.1.1",
 		"pear-pear.php.net/net_ldap2": ">=2.0.12",
 		"kolab/Net_LDAP3": "dev-master"
 	},
 	"minimum-stability": "dev"
 }
diff --git a/lib/Kolab/CardDAV/Plugin.php b/lib/Kolab/CardDAV/Plugin.php
index f579e45..053fee0 100644
--- a/lib/Kolab/CardDAV/Plugin.php
+++ b/lib/Kolab/CardDAV/Plugin.php
@@ -1,225 +1,225 @@
 <?php
 
 /**
  * Extended CardDAV plugin for the Kolab DAV server
  *
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2013, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 namespace Kolab\CardDAV;
 
 use Sabre\DAV;
 use Sabre\DAVACL;
 use Sabre\CardDAV;
 use Sabre\VObject;
 
 
 /**
  * Extended CardDAV plugin to tweak data validation
  */
 class Plugin extends CardDAV\Plugin
 {
     // make already parsed vcard blocks available for later use
     public static $parsed_vcard;
 
     // allow the backend to force a redirect Location
     public static $redirect_basename;
 
     /**
      * Initializes the plugin
      *
      * @param DAV\Server $server
      * @return void
      */
     public function initialize(DAV\Server $server)
     {
         parent::initialize($server);
 
         $server->on('beforeMethod', array($this, 'beforeMethod'));
         $server->on('afterCreateFile', array($this, 'afterWriteContent'));
         $server->on('afterWriteContent', array($this, 'afterWriteContent'));
     }
 
     /**
      * Adds all CardDAV-specific properties
      *
      * @param DAV\PropFind $propFind
      * @param DAV\INode $node
      * @return void
      */
     public function propFindEarly(DAV\PropFind $propFind, DAV\INode $node)
     {
         // publish global ldap address book for this principal
         if ($node instanceof DAVACL\IPrincipal && empty($this->directories) && \rcube::get_instance()->config->get('kolabdav_ldap_directory')) {
             $this->directories[] = self::ADDRESSBOOK_ROOT . '/' . $node->getName() . '/' . LDAPDirectory::DIRECTORY_NAME;
         }
 
         parent::propFindEarly($propFind, $node);
     }
 
     /**
      * Handler for beforeMethod events
      */
     public function beforeMethod($method, $uri)
     {
         if ($method == 'PUT' && $this->server->httpRequest->getHeader('If-None-Match') == '*') {
             // In-None-Match: * is only valid with PUT requests creating a new resource.
             // SOGo Conenctor for Thunderbird also sends it with update requests which then fail
             // in the Server::checkPreconditions().
             // See https://issues.kolab.org/show_bug.cgi?id=2589 and http://www.sogo.nu/bugs/view.php?id=1624
             // This is a work-around for the buggy SOGo connector and should be removed once fixed.
             if (strpos($this->server->httpRequest->getHeader('User-Agent'), 'Thunderbird/') > 0) {
                 unset($_SERVER['HTTP_IF_NONE_MATCH']);
             }
         }
     }
 
     /**
      * Inject some additional HTTP response headers
      */
     public function afterWriteContent($uri, $node)
     {
         // send Location: header to corrected URI
         if (self::$redirect_basename) {
             $path = explode('/', $uri);
             array_pop($path);
             array_push($path, self::$redirect_basename);
             $this->server->httpResponse->setHeader('Location', $this->server->getBaseUri() . join('/', array_map('urlencode', $path)));
             self::$redirect_basename = null;
         }
     }
 
     /**
      * Checks if the submitted iCalendar data is in fact, valid.
      *
      * An exception is thrown if it's not.
      *
      * @param resource|string $data
      * @return void
      */
     protected function validateVCard(&$data)
     {
         // If it's a stream, we convert it to a string first.
         if (is_resource($data)) {
             $data = stream_get_contents($data);
         }
 
         // Converting the data to unicode, if needed.
         $data = DAV\StringUtil::ensureUTF8($data);
 
         try {
             $vobj = VObject\Reader::read($data, VObject\Reader::OPTION_FORGIVING | VObject\Reader::OPTION_IGNORE_INVALID_LINES);
 
             if ($vobj->name == 'VCARD')
                 $this->parsed_vcard = $vobj;
         }
         catch (VObject\ParseException $e) {
             throw new DAV\Exception\UnsupportedMediaType('This resource only supports valid vcard data. Parse error: ' . $e->getMessage());
         }
 
         if ($vobj->name !== 'VCARD') {
             throw new DAV\Exception\UnsupportedMediaType('This collection can only support vcard objects.');
         }
 
         if (!isset($vobj->UID)) {
             throw new DAV\Exception\BadRequest('Every vcard must have a UID.');
         }
     }
 
     /**
      * Converts a vcard blob to a different version, or jcard.
      *
      * (optimized version that skips parsing and re-serialization if possible)
      *
      * @param string $data
      * @param string $target
      * @return string
      */
     protected function convertVCard($data, $target)
     {
         $version = 'vcard3';
-        if (preg_match('/VERSION:(\d)/', $data, $m)) {
+        if (is_string($data) && preg_match('/VERSION:(\d)/', $data, $m)) {
             $version = 'vcard' . $m[1];
         }
 
         // no conversion needed
         if ($target == $version) {
             return $data;
         }
 
         return parent::convertVCard($data, $target);
     }
 
     /**
      * This function handles the addressbook-query REPORT
      *
      * This report is used by the client to filter an addressbook based on a
      * complex query.
      *
      * @param \DOMNode $dom
      * @return void
      */
     protected function addressbookQueryReport($dom)
     {
         $node = $this->server->tree->getNodeForPath(($uri = $this->server->getRequestUri()));
         console(__METHOD__, $uri);
 
         // fix some bogus parameters in queries sent by the SOGo connector.
         // issue submitted in http://www.sogo.nu/bugs/view.php?id=2655
         $xpath = new \DOMXPath($dom);
         $xpath->registerNameSpace('card', Plugin::NS_CARDDAV);
 
         $filters = $xpath->query('/card:addressbook-query/card:filter');
         if ($filters->length === 1) {
             $filter = $filters->item(0);
             $propFilters = $xpath->query('card:prop-filter', $filter);
             for ($ii=0; $ii < $propFilters->length; $ii++) {
                 $propFilter = $propFilters->item($ii);
                 $name = $propFilter->getAttribute('name');
 
                 // attribute 'mail' => EMAIL
                 if ($name == 'mail') {
                     $propFilter->setAttribute('name', 'EMAIL');
                 }
 
                 $textMatches = $xpath->query('card:text-match', $propFilter);
                 for ($jj=0; $jj < $textMatches->length; $jj++) {
                     $textMatch = $textMatches->item($jj);
                     $collation = $textMatch->getAttribute('collation');
 
                     // 'i;unicasemap' is a non-standard collation
                     if ($collation == 'i;unicasemap') {
                         $textMatch->setAttribute('collation', 'i;unicode-casemap');
                     }
                 }
             }
         }
 
         // query on LDAP node: pass along filter query
         if ($node instanceof LDAPDirectory) {
             $query = new CardDAV\AddressBookQueryParser($dom);
             $query->parse();
 
             // set query and ...
             $node->setAddressbookQuery($query);
         }
 
         // ... proceed with default action
         parent::addressbookQueryReport($dom);
     }
 }
\ No newline at end of file
diff --git a/lib/Kolab/Utils/VObjectUtils.php b/lib/Kolab/Utils/VObjectUtils.php
index 9131597..7dbcb06 100644
--- a/lib/Kolab/Utils/VObjectUtils.php
+++ b/lib/Kolab/Utils/VObjectUtils.php
@@ -1,93 +1,98 @@
 <?php
 
 /**
  * Utility class providing functions for VObject data encoding
  *
  * @author Thomas Bruederli <bruederli@kolabsys.com>
  *
  * Copyright (C) 2013, Kolab Systems AG <contact@kolabsys.com>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as
  * published by the Free Software Foundation, either version 3 of the
  * License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 namespace Kolab\Utils;
 
 use Sabre\VObject\Property;
 
 /**
  * Helper class proviting utility functions for VObject data encoding
  */
 class VObjectUtils
 {
     /**
      * Convert an object URI into a valid UID value
      */
     public static function uri2uid($uri, $suffix = '')
     {
         $base = basename($uri, $suffix);
         $uid = strtr($base, array('%2F' => '/'));
 
         // assume full URL encoding
         if (preg_match('/%[A-F0-9]{2}/', $uid)) {
             return urldecode($base);
         }
 
         return $uid;
     }
 
     /**
      * Encode an object UID into a valid URI
      */
     public static function uid2uri($uid, $suffix = '')
     {
         $encode = strpos($uid, '/') !== false;
         return ($encode ? urlencode($uid) : $uid) . $suffix;
     }
 
     /**
      * Create a Sabre\VObject\Property instance from a PHP DateTime object
      *
      * @param string Property name
      * @param object DateTime
      */
     public static function datetime_prop($root, $name, $dt, $utc = false)
     {
         if ($utc) {
             $dt->setTimeZone(new \DateTimeZone('UTC'));
         }
 
-        $vdt = $root->createProperty($name);
-        $vdt->setValue($dt);
+        $vdt = $root->createProperty($name, null, null, $dt->_dateonly ? 'DATE' : 'DATE-TIME');
+        $value = $dt;
 
         if ($dt->_dateonly) {
-            $vdt['VALUE'] = 'DATE';
+            // $vdt['VALUE'] = 'DATE';
+            // set date value as string as a temporary fix for
+            // https://github.com/fruux/sabre-vobject/issues/217
+            $value = $dt->format('Y-m-d');
         }
 
+        $vdt->setVAlue($value);
+
         return $vdt;
     }
 
     /**
      * Copy values from one hash array to another using a key-map
      */
     public static function map_keys($values, $map)
     {
         $out = array();
         foreach ($map as $from => $to) {
             if (isset($values[$from]))
                 $out[$to] = $values[$from];
         }
         return $out;
     }
 
 }
\ No newline at end of file