Hi,

Seem that's issues come from Slider Revolution itself. You can see here:

https://codecanyon.net/item/slider-revolution-responsive-wordpress-plugin/2751380/comments?page=933#comment_21097714

Those are just warning not errors, you can disable warnings notifications in wordpress.

In that case, you can replace this line from your wp-config.php file:

define('WP_DEBUG', false);

with this:

ini_set('display_errors','Off');
ini_set('error_reporting', E_ALL );
define('WP_DEBUG', false);
define('WP_DEBUG_DISPLAY', false);

I hope that helps you out there!

Also, I recommend you update PHP to higher version to make everything running fine as author of plugin recommend.

Thanks