502 Bad Gateway error encountered by Nginx + PHP (php-fpm)

502 Bad Gateway error encountered by Nginx + PHP (php-fpm)

502 errors often pop up when using Nginx. Of course, errors cannot be ignored.

Nginx has just started to be used. If there are problems, there are opportunities for improvement. Let’s study the cause of the problem.

Check the error log first. The difference between Nginx and Apache is that PHP script errors will not appear in the Nginx log. So when a 502 error occurs, you must check the php-fpm log. The next article will introduce how to call it out. Specific error log of php-fpm.

By checking the error.log of php-fpm, you can find that the execution time of some PHP programs exceeds the waiting time of Nginx. You can appropriately increase the FastCGI timeout time in the nginx.conf configuration file.

According to this article

http://rtcamp.com/wordpress-nginx/tutorials/php/increase-script-execution-time/

1) Modify the execution time of the php script from 30s to 300s, modify php. ini

If you don’t know the location, you can find it from phpinfo()

In Apache, you only need to modify this step, but in Nginx, you need two more steps

2) Modify php-fpm configuration

vim /etc/php-fpm.d/www.conf

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3) Modify Nginx configuration

vim /etc/nginx/conf.d/www.conf

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Next, restartphp-fpm and Nginx

can see the effect.

In addition, if the number of php-cgi processes is not enough, the php execution time is long, or the php-cgi process dies, a 502 error will occur.

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