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Title: Sites are unavailable with HTTP 503 error: failed to make connection to backend:
Post by: Suhitha on Aug 16, 2025, 02:55 AM

Symptoms

Websites hosted on the Plesk server are returning an HTTP 503 Service Unavailable error.
There are the following records in /var/www/vhosts/example.com/logs/error_log file:

Code Select

[proxy:error] [pid 4322:tid 139839798191872] (2)No such file or directory: AH02454: FCGI: attempt to connect to Unix domain socket /var/www/vhosts/system/example.com/php-fpm.sock (*) failed
[proxy_fcgi:error] [pid 4322:tid 139839798191872] [client 203.0.113.2:58526] AH01079: failed to make connection to backend: httpd-UDS

Cause

Unclear.

Resolution

1. Connect to the server via SSH.

2. Run the following command:
#plesk repair web

Cobra Forum

Plesk Panel => Webserver => Topic started by: Suhitha on Aug 16, 2025, 02:55 AM