下载docx文件时出错

I am generating docx and download from server.

private static function downloadFile($fileDir)
{
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename=' . basename($fileDir));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($fileDir));
    readfile($fileDir);
}

This is save function. if I open file in the temporary dir from server, it works. But after download, I have error "The file is damaged" . I try to restore the file and afrer restoring all ok. Where is error?

Before readfile($fileDir), try to run ob_clean() and flush() to clean (erase) and flush the output buffer.

Quoting from PHP's manual about flush():

flush() may not be able to override the buffering scheme of your web server and it has no effect on any client-side buffering in the browser. It also doesn't affect PHP's userspace output buffering mechanism. This means you will have to call both ob_flush() and flush() to flush the ob output buffers if you are using those.