diff --git a/lib/Group/backend.php b/lib/Group/backend.php
index c70bd6665cb871274d50c3c4b4d711cf0e563780..f34c340be8cfbf4ab6cb07ad787204d2f13b9802 100644
--- a/lib/Group/backend.php
+++ b/lib/Group/backend.php
@@ -33,7 +33,7 @@ abstract class OC_GROUP_BACKEND {
 	 *
 	 * @param  string  $groupName  The name of the group to create
 	 */
-	abstract public static function createGroup($groupName);
+	public static function createGroup($groupName){}
 
 	/**
 	 * Check if a user belongs to a group
@@ -41,7 +41,7 @@ abstract class OC_GROUP_BACKEND {
 	 * @param  string  $username   Name of the user to check
 	 * @param  string  $groupName  Name of the group
 	 */
-	abstract public static function inGroup($username, $groupName);
+	public static function inGroup($username, $groupName){}
 
 	/**
 	 * Add a user to a group
@@ -49,7 +49,7 @@ abstract class OC_GROUP_BACKEND {
 	 * @param  string  $username   Name of the user to add to group
 	 * @param  string  $groupName  Name of the group in which add the user
 	 */
-	abstract public static function addToGroup($username, $groupName);
+	public static function addToGroup($username, $groupName){}
 
 	/**
 	 * Remove a user from a group
@@ -57,18 +57,18 @@ abstract class OC_GROUP_BACKEND {
 	 * @param  string  $username   Name of the user to remove from group
 	 * @param  string  $groupName  Name of the group from which remove the user
 	 */
-	abstract public static function removeFromGroup($username,$groupName);
+	public static function removeFromGroup($username,$groupName){}
 
 	/**
 	 * Get all groups the user belongs to
 	 *
 	 * @param  string  $username  Name of the user
 	 */
-	abstract public static function getUserGroups($username);
+	public static function getUserGroups($username){}
 
 	/**
 	 * get a list of all groups
 	 *
 	 */
-	abstract public static function getGroups();
+	public static function getGroups(){}
 }
diff --git a/lib/User/backend.php b/lib/User/backend.php
index ab053661f88d1d054abdc124260e973af5d7327f..0483d72bf02f1f98cdc91323f7d1659113ebd5a5 100644
--- a/lib/User/backend.php
+++ b/lib/User/backend.php
@@ -35,7 +35,7 @@ abstract class OC_USER_BACKEND {
 	 * @param  string  $username  The username of the user to create
 	 * @param  string  $password  The password of the new user
 	 */
-	abstract public static function createUser($username, $password);
+	public static function createUser($username, $password){}
 
 	/**
 	 * Try to login a user
@@ -43,18 +43,18 @@ abstract class OC_USER_BACKEND {
 	 * @param  string  $username  The username of the user to log in
 	 * @param  string  $password  The password of the user
 	 */
-	abstract public static function login($username, $password);
+	public static function login($username, $password){}
 
 	/**
 	 * Check if some user is logged in
 	 *
 	 */
-	abstract public static function isLoggedIn();
+	public static function isLoggedIn(){}
 
 	/**
 	 * Generate a random password
 	 */
-	abstract public static function generatePassword();
+	public static function generatePassword(){}
 
 	/**
 	 * Set the password of a user
@@ -62,7 +62,7 @@ abstract class OC_USER_BACKEND {
 	 * @param  string  $username  User who password will be changed
 	 * @param  string  $password  The new password for the user
 	 */
-	abstract public static function setPassword($username, $password);
+	public static function setPassword($username, $password){}
 
 	/**
 	 * Check if the password of the user is correct
@@ -70,12 +70,12 @@ abstract class OC_USER_BACKEND {
 	 * @param  string  $username  Name of the user
 	 * @param  string  $password  Password of the user
 	 */
-	abstract public static function checkPassword($username, $password);
+	public static function checkPassword($username, $password){}
 
 
 	/**
 	 * get a list of all users
 	 *
 	 */
-	abstract public static function getUsers();
+	public static function getUsers(){}
 }
diff --git a/lib/fileobserver.php b/lib/fileobserver.php
index 08a67521f037bdcd957ba9c1178f760337b88ee5..ac9f2513c7bff34caa0ccc39c096d3da3056209e 100644
--- a/lib/fileobserver.php
+++ b/lib/fileobserver.php
@@ -41,7 +41,7 @@ class OC_FILEOBSERVER{
 		}
 	}
 	
-	public function notify($path,$action){}
+	public function notify($path,$action,$storage){}
 }
 
 /**
diff --git a/lib/helper.php b/lib/helper.php
index 4fff7c28fead34d4ce3be064bf2c0ebabdb8c0cd..7c7fe2757e7d94355fc420c5c8a1c7618d6d5f87 100644
--- a/lib/helper.php
+++ b/lib/helper.php
@@ -60,8 +60,8 @@ class OC_HELPER {
 		global $SERVERROOT;
 		global $WEBROOT;
 		// Check if the app is in the app folder
-		if( file_exists( "$SERVERROOT/apps/img/$app/$file" )){
-			return "$WEBROOT/apps/img/$app/$file";
+		if( file_exists( "$SERVERROOT/apps/img/$app/$image" )){
+			return "$WEBROOT/apps/img/$app/$image";
 		}
 		return "$WEBROOT/$app/img/$image";
 	}