FATAL ERROR with WP 5.5

I have this error on when clicking on customisation since my host upgraded WP to 5.5

I have installed the jquery plugin but that has had no effect.

Error below:

Fatal error: Uncaught Error: Call to undefined function gutenberg_can_edit_post_type() in /var/www/wp-content/themes/enfold/config-gutenberg/class-avia-gutenberg.php:563 Stack trace: #0 /var/www/wp-content/themes/enfold/config-gutenberg/class-avia-gutenberg.php(423): Avia_Gutenberg->can_use_block_editor(‘post’, true) #1 /var/www/wp-content/themes/enfold/config-gutenberg/class-avia-gutenberg.php(458): Avia_Gutenberg->init_force_classic_post_types() #2 /var/www/wp-content/themes/enfold/config-gutenberg/class-avia-gutenberg.php(533): Avia_Gutenberg->get_force_classic_post_types() #3 /var/www/wp-content/themes/enfold/config-gutenberg/class-avia-gutenberg.php(661): Avia_Gutenberg->force_classic_editor(‘page’) #4 /var/www/wp-includes/class-wp-hook.php(287): Avia_Gutenberg->handler_display_post_states(Array, Object(WP_Post)) #5 /var/www/wp-includes/plugin.php(206): WP_Hook->apply_filters(Array, Array) #6 /var/www/wp-admin/includes/template.php(2221): apply_filters(‘display_post_st…’, Array, Object(WP_Post)) #7 /var/www/wp-incl in /var/www/wp-content/themes/enfold/config-gutenberg/class-avia-gutenberg.php on line 563
There has been a critical error on your website. Please check your site admin email inbox for instructions.