Fatal error: Uncaught TypeError: array_merge(): Argument #6 must be of type array, null given in /var/www/html/wp-includes/widgets.php:1346
Stack trace:
#0 /var/www/html/wp-includes/widgets.php(1346): array_merge(Array, Array, Array, Array, Array, NULL, Array, Array, Array, Array, Array, Array)
#1 /var/www/html/wp-includes/widgets.php(1291): retrieve_widgets(true)
#2 /var/www/html/wp-includes/class-wp-hook.php(326): _wp_sidebars_changed('Responsive')
#3 /var/www/html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#4 /var/www/html/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#5 /var/www/html/wp-includes/theme.php(3496): do_action('after_switch_th...', 'Responsive', Object(WP_Theme))
#6 /var/www/html/wp-includes/class-wp-hook.php(324): check_theme_switched('')
#7 /var/www/html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#8 /var/www/html/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#9 /var/www/html/wp-settings.php(695): do_action('init')
#10 /var/www/html/wp-config.php(101): require_once('/var/www/html/w...')
#11 /var/www/html/wp-load.php(50): require_once('/var/www/html/w...')
#12 /var/www/html/wp-blog-header.php(13): require_once('/var/www/html/w...')
#13 /var/www/html/index.php(17): require('/var/www/html/w...')
#14 {main}
thrown in /var/www/html/wp-includes/widgets.php on line 1346