Custom Nissan Navara Import X

Fatal error: Uncaught Error: Call to undefined method Avada_Layout::add_class() in /home/ststrimc/public_html/wp-content/themes/Avada-Child-Theme/single-avada_portfolio.php:18 Stack trace: #0 /home/ststrimc/public_html/wp-includes/template-loader.php(106): include() #1 /home/ststrimc/public_html/wp-blog-header.php(19): require_once('/home/ststrimc/...') #2 /home/ststrimc/public_html/index.php(17): require('/home/ststrimc/...') #3 {main} thrown in /home/ststrimc/public_html/wp-content/themes/Avada-Child-Theme/single-avada_portfolio.php on line 18