Recently I just test my new website in document download section, I use readfile() function to read the file that will be downloaded. When I test it I found an error messege that indicate readfile() function disabled by my hosting provider,so I change my readfile() using fopen() and fgets() function. I test it it and work fine now :)

$handle = @fopen("static/dokumen/".$datafile[0]->file_name, "r");
if ($handle) {
while (!feof($handle)) {
$buffer = fgets($handle, 4096);
echo $buffer;
}
fclose($handle);
}