Fatal error: Uncaught Error: Call to undefined function register_block_type() in /home/stasse21/domains/stassen-installatie.nl/public_html/wp-content/plugins/responsive-add-ons/src/blocks/block-newsletter/index.php:14 Stack trace: #0 /home/stasse21/domains/stassen-installatie.nl/public_html/wp-includes/class-wp-hook.php(298): responsive_blocks_register_newsletter_block('') #1 /home/stasse21/domains/stassen-installatie.nl/public_html/wp-includes/class-wp-hook.php(323): WP_Hook->apply_filters(NULL, Array) #2 /home/stasse21/domains/stassen-installatie.nl/public_html/wp-includes/plugin.php(453): WP_Hook->do_action(Array) #3 /home/stasse21/domains/stassen-installatie.nl/public_html/wp-settings.php(448): do_action('init') #4 /home/stasse21/domains/stassen-installatie.nl/public_html/wp-config.php(102): require_once('/home/stasse21/...') #5 /home/stasse21/domains/stassen-installatie.nl/public_html/wp-load.php(37): require_once('/home/stasse21/...') #6 /home/stasse21/domains/stassen-installatie.nl/public_html/wp-blog-header.php(13 in /home/stasse21/domains/stassen-installatie.nl/public_html/wp-content/plugins/responsive-add-ons/src/blocks/block-newsletter/index.php on line 14