502 Bad Gateway The proxy server received an invalid response from an upstream server

打開網站一直報錯，查看了一下nginx錯誤日誌，發現不少的報錯：

2018/12/24 11:02:51 [alert] 20026#20026: *33113943 socket() failed (24: Too many open files) while connecting to upstream, client:

查看nginx設置的可打開文件大小

1.查看nginx的進程號

ps -elf | grep nginx

2.根據查出來的進程號查看進程詳情

cat /proc/進程號/limits

其中Max open files是1024，修改配置值，在nginx中修改
worker_rlimit_nofile 65535;

events { 
        worker_connections 65535; 
}

在nginx配置文件中加上這幾行

重啓nginx，問題解決