Unable to start the Nginx Service on a Plesk Server: [emerg] unknown directive "brotli" in /etc/nginx/conf.d/brotli.conf:1

Symptoms

• Nginx service fails to start due to one or more errors of modules which cannot be properly loaded such as brotli and/or others:

  [emerg] 13807#13807: unknown directive "brotli" in /etc/nginx/conf.d/brotli.conf:1

• All websites are showing "Web Server’s Default Page"

• While checking the nginx packages, third party sources are found installed and the one provided by Plesk (sw-nginx) removed:

  # dpkg -l | grep nginx
  
  ii nginx 
  ii nginx-common 
  rc sw-nginx

Cause

The nginx installed packages are not provided by Plesk.

Resolution

1. Remove all third party nginx packages:

   # dpkg --remove nginx nginx-common && dpkg --purge nginx nginx-common

2. Remove the Nginx web server and reverse proxy server component via Plesk Installer if found installed under Web hosting section.

3. Remove leftovers of the Plesk sw-nginx package:

   # dpkg --purge sw-nginx

4. Install and enable Plesk provided Nginx as instructed here.