Warning: Trying to access array offset on value of type bool in /DISK2/WWW/cmun.cz/praha/wp-includes/theme.php on line 2241

Fatal error: Uncaught ArgumentCountError: array_merge() does not accept unknown named parameters in /DISK2/WWW/cmun.cz/praha/wp-includes/widgets.php:1160
Stack trace:
#0 /DISK2/WWW/cmun.cz/praha/wp-includes/widgets.php(1160): array_merge(wp_inactive_widgets: Array, primary-widget-area: Array, secondary-widget-area: Array, first-footer-widget-area: Array, second-footer-widget-area: Array, third-footer-widget-area: Array, fourth-footer-widget-area: Array)
#1 /DISK2/WWW/cmun.cz/praha/wp-includes/widgets.php(1115): retrieve_widgets(true)
#2 /DISK2/WWW/cmun.cz/praha/wp-includes/class-wp-hook.php(288): _wp_sidebars_changed('Twenty Ten')
#3 /DISK2/WWW/cmun.cz/praha/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array)
#4 /DISK2/WWW/cmun.cz/praha/wp-includes/plugin.php(453): WP_Hook->do_action(Array)
#5 /DISK2/WWW/cmun.cz/praha/wp-includes/theme.php(2749): do_action('after_switch_th...', 'Twenty Ten', Object(WP_Theme))
#6 /DISK2/WWW/cmun.cz/praha/wp-includes/class-wp-hook.php(286): check_theme_switched('')
#7 /DISK2/WWW/cmun.cz/praha/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array)
#8 /DISK2/WWW/cmun.cz/praha/wp-includes/plugin.php(453): WP_Hook->do_action(Array)
#9 /DISK2/WWW/cmun.cz/praha/wp-settings.php(450): do_action('init')
#10 /DISK2/WWW/cmun.cz/praha/wp-config.php(97): require_once('/DISK2/WWW/cmun...')
#11 /DISK2/WWW/cmun.cz/praha/wp-load.php(37): require_once('/DISK2/WWW/cmun...')
#12 /DISK2/WWW/cmun.cz/praha/wp-blog-header.php(13): require_once('/DISK2/WWW/cmun...')
#13 /DISK2/WWW/cmun.cz/praha/index.php(17): require('/DISK2/WWW/cmun...')
#14 {main}
  thrown in /DISK2/WWW/cmun.cz/praha/wp-includes/widgets.php on line 1160