I read a solution here: http://wordpress.org/support/topic/not-able-to-create-a-new-download . Cesareino wrote in that forum 3 days ago this:
“issue is related to a change in download-manager.php at line 480
if($_POST){ //old line 4.5.9
if(isset($_POST)){ //new line 4.5.91
plugin works again using the first line”.
It works. Excuse me for my bad English but I know it so and so.
