Fatal error: Class 'Elementor\Control_Base' not found

If you see this error message after updating your Elementor, or if you just installed a new Elementor:

"Fatal error: Class 'Elementor\Control_Base' not found in /wp-content/plugins/nextend-smart-slider3-pro/includes/integrations/Elementor.php on line 76"

then update your Smart Slider 3, and it will solve your problem!