I download a file but it gives invalid file in return.
Here\'s my download_content.php
Your $filename variable contains whole path as below
header("Content-Disposition: attachment; filename=$filename");
Do like this
$newfilename = explode("/",$filename);
$newfilename = $newfilename[count($newfilename)-1];
$fsize = filesize($filename);
Then pass new variable into header
header("Content-Disposition: attachment; filename=".$newfilename);
header("Content-length: $fsize");
//newline added as below
ob_clean();
flush();
readfile($filename);