Website is showing web server default page.
There are both index.html file generated by Plesk, and index.php in the document root of example.com :
# ls /var/www/vhosts/example.com/httpdocs/ | grep index
In the Apache configuration file of this domain index.html is set to have higher priority and, therefore, is displayed:
# cat /var/www/vhosts/system/example.com/conf/httpd.conf |grep DirectoryIndex
DirectoryIndex “index.html” “index.cgi” “index.pl” “index.php” “index.xhtml” “index.htm” “index.shtml”
Connect to a Plesk server via SSH.
Rename or remove index.html:
# mv /var/www/vhosts/example.com/httpdocs/index.html /var/www/vhosts/example.com/httpdocs/index.html.bak