If you updated your WordPress website and your web hosting PHP version from PHP 5.* to PHP 7.*, you will likely encounter an error like Deprecated: Directive ‘allow_url_include’ is deprecated in Unknown on line 0 especially if you are hosting with Hostgator.
To fix it, simply log in to your cPanel or FTP Access and edit the .htaccess file. Remove the line below
# php — BEGIN cPanel-generated handler, do not edit
# Set the “ea-php74” package as the default “PHP” programming language.
AddHandler application/x-httpd-ea-php74 .php .php7 .phtml
# php — END cPanel-generated handler, do not edit