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 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-includes/class-wp-hook.php:341 Stack trace: #0 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters(NULL, Array) #1 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-includes/plugin.php(522): WP_Hook->do_action(Array) #2 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-includes/widgets.php(1884): do_action('widgets_init') #3 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-includes/class-wp-hook.php(341): wp_widgets_init('') #4 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-includes/class-wp-hook.php(365): WP_Hook->apply_filters(NULL, Array) #5 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-includes/plugin.php(522): WP_Hook->do_action(Array) #6 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-settings.php(771): do_action('init') #7 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-config.php(91): require_once('/www/htdocs/v08...') #8 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-load.php(50): require_once('/www/htdocs/v08...') #9 /www/htdocs/v081112/wordpress.mvendersbach.de/wp-blog-header.php(13): require_once('/www/htdocs/v08...') #10 /www/htdocs/v081112/wordpress.mvendersbach.de/index.php(17): require('/www/htdocs/v08...') #11 {main} thrown in /www/htdocs/v081112/wordpress.mvendersbach.de/wp-includes/class-wp-hook.php on line 341