This issue is mostly seen when migrating CMS sites from Plesk to WHM/cPanel. The migration goes well - there are no errors during the transfer - the php versions are the same on both servers. However when you update DNS or your host file to view the site on the new server the page doesn't load or there is unexpected content displayed.
This is a relatively simple fix.
* Log into the server via SSH (putty for Windows users)
* Change directory to the cPanel account you need to check
* Change to the public_html directory.
* Type in the following and hit enter: ll
* Check if there is an index.html file if it exists:
* mv index.html index-old.html
That should fix the issue - if you reload the site it should now load.
Most CMS are based on PHP - they don't use .html files - the index.html is processed before the index.php file - so until the .html file is renamed or deleted the site will not load correctly.