nginx 报错502

502一般都是转发到php-fpm时出现问题

打开 nginx日志。一般路径

/var/log/nginx

查看里面。显示

pstream sent too big header while reading response header from upstream, client: 

说的是你请求头太大了，于是在nginx.conf增加两句

client_header_buffer_size 128k;
large_client_header_buffers 4 128k;

proxy_buffer_size  128k;
proxy_buffers   32 32k;
proxy_busy_buffers_size 128k

问题解决