Problem solved - It is not a Manager problem - This issue was a Nginx client configuration issue /limit. The client_max_body_size directive assigns the maximum accepted body size of client request, indicated by the line Content-Length in the header of request. If import file size is greater than the one specified in the nginx.conf file or if it is not specified, then the client gets the error “Request Entity Too Large” (413). To fix this issue edit your nginx.conf.
sudo nano /etc/nginx/nginx.conf
add the following in the http section
# set client body size to 10M #
Save the nginix config file, then restart the nginx service to reload the new config
sudo service nginx reload
Help found on this page http://www.cyberciti.biz/faq/linux-unix-bsd-nginx-413-request-entity-too-large/
by Vivek Gite