Unable to repair web server configuration in Plesk: Can not reload proxy server

Symptoms

• If an SSL certificate has been changed, it is not returned by a web server, and the old one is used instead.

• New domains show Plesk Default Page, Plesk login page or fail to load with ERR_SSL_PROTOCOL_ERROR.

• A cloned website shows 404 error.

• Domains assigned to a newly added IP address do not load with:

  PLESK_INFO: ERR_CONNECTION_REFUSED

• When repairing web-server configuration using Plesk repair tool, the operation fails with:

  # plesk repair web example.com -y
  Checking web server configuration. Please wait
  File not found: example.com.conf ...................................... [ERROR]
  Repairing web server configuration for the domain example.com
  ...
  [FAILED]
  ...
  Can not reload proxy server:

• When checking nginx status manually, it is marked as disabled:

  # service nginx status
  ● nginx.service - Startup script for nginx service
  Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
  Drop-In: /lib/systemd/system/nginx.service.d
  └─respawn.conf
  Active: activating (auto-restart) (Result: exit-code) since Tue 2021-12-21 15:19:21 UTC; 1s ago
  Process: 8829 ExecStartPre=/bin/sh -c [ '${NGINX_ENABLED}' = 'yes' ] || { echo Not starting nginx as it is disabled
  Main PID: 4630 (code=exited, status=0/SUCCESS)

  or dead:

  # service nginx status
  nginx dead but pid file exists

  but nginx support is enabled in Plesk:

  # plesk sbin nginxmng -s
  Enabled

• nginx error log is empty and is not filled with new records:

  # ls -l /var/log/nginx/error.log
  -rw-r--r-- 1 root root 0 Dec 21 14:59 /var/log/nginx/error.log

Cause

nginx configuration/installation is corrupted.

Resolution

1. Connect to a Plesk server via SSH.

2. Reenable nginx reverse proxy using these commands:

   # plesk sbin nginxmng --disable

   # plesk sbin nginxmng --enable

3. Check nginx status:

   # service nginx status

    

   If the service is still down, reinstall nginx reverse proxy:

1. Remove nginx reverse proxy:

   # plesk installer --select-release-current --remove-component nginx

2. Install nginx reverse proxy using the following command:

   # plesk installer --select-release-current --install-component nginx

3. Check nginx reverse proxy status:

   # plesk sbin nginxmng --status

   If it is "Disabled", enable the component:

   # plesk sbin nginxmng --enable