         if error != nil {
             let blocks = self.backgroundTaskMap[session.configuration.identifier]
             if blocks?.failure != nil { //Swift bug. Can't use && with block (radar: 17469794)
-                blocks?.failure!(error)
+                blocks?.failure!(error, nil)
                 cleanupBackground(session.configuration.identifier)
             }
         }

        :param: success The block that is run on a sucessful HTTP Request.
        :param: failure The block that is run on a failed HTTP Request.
    */
    public func DELETE(url: String, parameters: Dictionary<String,AnyObject>?, success:((HTTPResponse) -> Void)!, failure:((NSError) -> Void)!)  {
        var opt = self.create(url, method:.DELETE, parameters: parameters,success,failure)
        if opt != nil {
            opt!.start()

        :param: success The block that is run on a sucessful HTTP Request.
        :param: failure The block that is run on a failed HTTP Request.
    */
    public func GET(url: String, parameters: Dictionary<String,AnyObject>?, success:((HTTPResponse) -> Void)!, failure:((NSError, HTTPResponse?) -> Void)!) {
        var opt = self.create(url, method:.GET, parameters: parameters,success,failure)
        if opt != nil {
            opt!.start()
