mr srirang,
you are using nginx upload module right. 413 will be thrown when the request entity too large .set the field like this
upload_max_output_body_len 0;
0 means there will be no restriction for the file size u r uploading .check in ur remote machine config .if u did nt specify the above .the default will be 100kb. and another thing there is no file limit .u can change to whatever the size u want to upload.
if u still get that connection was reset
try like this
comment the access_log path in your config file
then upload
may be because access permission in writing log file.