Unable to add "location /" to additional nginx directives for domain in Plesk: nginx: [emerg] duplicate location "/"

Symptoms

If try adding the below directives in Plesk in Domains > example.com > Apache & nginx Settings > Additional nginx directives:

CONFIG_TEXT: location / {
..........
}

The following error occurs:

PLESK_ERROR: Invalid nginx configuration: nginx: [emerg] duplicate location "/" in /data/www/system/example.com/conf/vhost_nginx.conf:1 nginx: configuration file /etc/nginx/nginx.conf test failed

Cause

Location / is already defined in the main domain configuration file /var/www/vhosts/system/example.com/conf/nginx.conf.

Resolution

If additional directives should be added to the location /, it can be done using the custom virtual hosts configuration templates. See the below documentation article for more details:

Changing Virtual Hosts Settings Using Configuration Templates

Warning: The changes in the virtual hosts configuration templates are applied to all domains on the server.