1.0 502 Bad Gateway
After the update of Linux on the web server, the website would not open in the browser. Instead the following error was displayed.
502 Bad Gateway
First we check the nginx server.
$ systemctl status nginx
● nginx.service - A high performance web server and a reverse proxy server
Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
Active: active (running) since Thu 2019-03-21 15:16:47 UTC; 16h ago
Main PID: 1354 (nginx)
Tasks: 8 (limit: 1158)
├─1354 nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
└─1355 nginx: worker process
Warning: Journal has been rotated since unit was started.
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A routine software update on the server running nginx was done. After that the website stopped opening in the browser window and
502 Bad Gateway error along with the nginx version number was displayed. Looking in the log file showed an entry like,
2014/06/26 11:09:53 [crit] 2539#0: *15 connect() to unix:/tmp/php-fpm.sock failed (13: Permission denied) while connecting to upstream, client: 127.0.0.1, server: www.example.com, request: "GET /foo HTTP/1.1", upstream: "fastcgi://unix:/tmp/php-fpm.sock:", host: "www.example.com"
The problem was solved after the following lines were un-commented in the file, /etc/php5/fpm/pool.d/www.conf
listen.owner = www-data
listen.group = www-data
The same file, /etc/php5/fpm/pool.d/www.conf, had the lines
user = www-data
group = www-data
Also, the nginx configuration file /etc/nginx/nginx.conf had the user and group settings,
user www-data www-data;
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