Divi compatibility

I tried installed Ultimate DebugBar on WP with Divi theme builder. The server crashed with error log:

PHP Fatal error:  Uncaught Error: Call to undefined function et_core_cache_dir() in /var/www/wp-content/themes/Divi/includes/builder/feature/AjaxCache.php:236
Stack trace:
#0 /var/www/wp-content/themes/Divi/includes/builder/feature/AjaxCache.php(62): ET_Builder_Ajax_Cache->get_file_name()
#1 /var/www/wp-content/themes/Divi/includes/builder/feature/AjaxCache.php(177): ET_Builder_Ajax_Cache->file_exists()
#2 /var/www/wp-content/themes/Divi/includes/builder/feature/AjaxCache.php(124): ET_Builder_Ajax_Cache->delete_file()
#3 /var/www/wp-content/themes/Divi/includes/builder/feature/AjaxCache.php(137): ET_Builder_Ajax_Cache->load()
#4 /var/www/wp-includes/class-wp-hook.php(307): ET_Builder_Ajax_Cache->save()
#5 /var/www/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters()

I know nothing about WordPress, do you know the root cause?
I deleted the plugin folder and the entry in the wp_options table and the site was live again, so it is for sure the Ultimate DebugBar plugin that introduces this error.

Thank you