upstream sent invalid status "-1 Copy failed" while reading response header from upstream

[NaZz]

Hello, thank you for help.
Yes I have already tried that. (tried putting it to client_max_body_size
20M;) 
My php post_max_size and max_upload_filesize are = 20M (for the sake of
fixing this problem)

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,254276,254288#msg-254288