PHP-FPM not working, 503 Service Unavailable

My website suddenly got the following error
503 Service Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

I checked the error log of the domain name and found the following code

it seem the PHP-FPM stopped working, how to fix it?

[Thu Apr 28 03:34:04.581381 2022] [proxy:error] [pid 969:tid 140569548404480] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /opt/alt/php-fpm74/usr/var/sockets/mydomain.sock (*) failed
[Thu Apr 28 03:34:04.581404 2022] [proxy_fcgi:error] [pid 969:tid 140569548404480] [client 113.118.232.250:46144] AH01079: failed to make connection to backend: httpd-UDS
[Thu Apr 28 03:34:04.609360 2022] [proxy:error] [pid 968:tid 140569531619072] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /opt/alt/php-fpm74/usr/var/sockets/mydomain.sock (*) failed
[Thu Apr 28 03:34:04.609400 2022] [proxy_fcgi:error] [pid 968:tid 140569531619072] [client 92.247.181.45:46146] AH01079: failed to make connection to backend: httpd-UDS
[Thu Apr 28 03:34:05.585224 2022] [proxy:error] [pid 967:tid 140569422513920] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /opt/alt/php-fpm74/usr/var/sockets/mydomain.sock (*) failed
[Thu Apr 28 03:34:05.585250 2022] [proxy_fcgi:error] [pid 967:tid 140569422513920] [client 113.118.232.250:46148] AH01079: failed to make connection to backend: httpd-UDS
[Thu Apr 28 03:34:19.692806 2022] [proxy:error] [pid 968:tid 140569514833664] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /opt/alt/php-fpm74/usr/var/sockets/mydomain.sock (*) failed
[Thu Apr 28 03:34:19.692837 2022] [proxy_fcgi:error] [pid 968:tid 140569514833664] [client 82.146.56.36:46154] AH01079: failed to make connection to backend: httpd-UDS
[Thu Apr 28 03:34:31.446718 2022] [proxy:error] [pid 968:tid 140569659246336] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /opt/alt/php-fpm74/usr/var/sockets/mydomain.sock (*) failed
[Thu Apr 28 03:34:31.446743 2022] [proxy_fcgi:error] [pid 968:tid 140569659246336] [client 66.249.64.182:46156] AH01079: failed to make connection to backend: httpd-UDS
[Thu Apr 28 03:34:35.353507 2022] [proxy:error] [pid 968:tid 140569573582592] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /opt/alt/php-fpm74/usr/var/sockets/mydomain.sock (*) failed

There is no SOCKET connection in PHP-FPM 7.4 configuration of your MYDOMAIN.COM domain name. For PHP-FPM 7.4 you need to configure php 7.4 to add a plugin for mydoma.com.

systemctl status php-fpm74

if it is stopped, start it

systemctl start php-fpm74


if it's alive, try restarting it

systemctl restart php-fpm74

if that doesn't work, please post the contents of

journalctl -xeu php-fpm74