Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, non-static method OWA_Block::register_widget_sidebar() cannot be called statically in /customers/4/4/b/abp-bvp.be/httpd.www/wp-includes/class-wp-hook.php:307 Stack trace: #0 /customers/4/4/b/abp-bvp.be/httpd.www/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters('', Array) #1 /customers/4/4/b/abp-bvp.be/httpd.www/wp-includes/plugin.php(476): WP_Hook->do_action(Array) #2 /customers/4/4/b/abp-bvp.be/httpd.www/wp-includes/widgets.php(1854): do_action('widgets_init') #3 /customers/4/4/b/abp-bvp.be/httpd.www/wp-includes/class-wp-hook.php(307): wp_widgets_init('') #4 /customers/4/4/b/abp-bvp.be/httpd.www/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array) #5 /customers/4/4/b/abp-bvp.be/httpd.www/wp-includes/plugin.php(476): WP_Hook->do_action(Array) #6 /customers/4/4/b/abp-bvp.be/httpd.www/wp-settings.php(598): do_action('init') #7 /customers/4/4/b/abp-bvp.be/httpd.www/wp-config.php(99): require_once('/customers/4/4/...') #8 /customers/4/4/b/abp-bvp.be/httpd.www/wp-load.php(50): require_once('/customers/4/4/...') #9 /customers/4/4/b/abp-bvp.be/httpd.www/wp-blog-header.php(13): require_once('/customers/4/4/...') #10 /customers/4/4/b/abp-bvp.be/httpd.www/index.php(17): require('/customers/4/4/...') #11 {main} thrown in /customers/4/4/b/abp-bvp.be/httpd.www/wp-includes/class-wp-hook.php on line 307