Older versions of Revolution Slider do not support PHP 7. From Version 18.104.22.168 this issue should be rectified, but you might find that older versions that are bundled with themes may not support PHP 7.
If you have Revolution Slider plugin installed and you want to migrate your website to another location, but you got blank screen after import or your Revolution Slider is not activated after import but it was before export, the first thing you can do is to check your PHP version. We tested Revolution Slider and it was not working properly on PHP 7 because it throws fatal error and interrupts script execution.
Solution (two approaches):
1. Update Revolution Slider to the latest version that support PHP 7, or disable the slider.
2. Apply quick fix of the plugin source code.
Open file for edit /wp-content/plugins/revslider/inc_php/framework/db.class.php
Find the function called checkForErrors
and change the if statement below it to
The idea is make Revolution Slider to not rely on mysql_error function because it’s deprecated and removed in PHP 7.