求助：nginx配置问题，困扰很久了

[inCoding]

/log/error.jsp中报
[error] 3179#0: *25 upstream prematurely closed connection while reading response header from upstream,....错误

应用部署在resin4上，单独访问resin没问题。但是一通过nginx->resin就有问题
nginx配置如下

upstream image_processor {
server 10.10.92.10:8081;
}

server {
listen 80;
server_name up.t.sina.com;
client_max_body_size 500m;
client_body_timeout 1200;
client_body_buffer_size 1024k;
#charset koi8-r;

#access_log logs/host.access.log main;

# location / {
# root html;
# index index.html index.htm;
# }

location ~ (.*)$ {
proxy_pass http://image_processor;
proxy_next_upstream error timeout invalid_header http_500 http_502 http_503;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto https;
proxy_redirect off;
allow all;
}

[inCoding]

没人回答！