I'm trying to send a file from within a Kohana model to the browser, but as soon as I add a Content-Length header, the file doesn't start downloading right away. Now the problem seems to be that Kohana is already outputting buffers. An ob_clean at the begin of the script doesn't help this though. Also adding ob_get_length() to the Content-Length isn't helping since this just returns 0. The getFileSize() function returns the right number: if I run the script outside of Kohana, it works. I read that exit() still calls all destructors and it might be that something is outputted by Kohana afterwards, but I can't find out what exactly. Hope someone can help me out here... This is the piece of code I'm using: public function download() { header("Expires: ".gmdate("D, d M Y H:i:s",time()+(3600*7))." GMT\n"); header("Content-Type: ".$this->getFileType()."\n"); header("Content-Transfer-Encoding: binary\n"); header("Last-Modified: " . gmdate("D, d M Y H:i:s",$this->getCreateTime()) . " GMT\n"); header("Content-Length: ".($this->getFileSize()+ob_get_length().";\n"); header('Content-Disposition: attachment; filename="'.basename($this->getFileName())."\"\n\n"); ob_end_flush(); readfile($this->getFilePath()); exit(); }