Recently a client reached out concerning a critical error in WordPress using Avada when trying to access the wp-admin area of the website.
It appears that the problem is due to an issue with Revolution Slider, specifically a metabox function that’s including in the admin class. In order to fix this, you’ll need to look for the file /revslider/includes/framework/base-admin.class.php in your plugins directory and update the following line.
private static $arrMetaBoxes = ''; //option boxes that will be added to post
private static $arrMetaBoxes = array(); //option boxes that will be added to post
That should fix the issue and allow you to use your wp-admin area again.