Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, function "sub_nav_walker" not found or invalid function name in /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/class-wp-hook.php:308
Stack trace:
#0 /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/plugin.php(205): WP_Hook->apply_filters('karma_walker', Array)
#1 /usr/home/globenet/domains/wazony24.pl/public_html/wp-content/themes/karma/framework/karma-megamenu.php(35): apply_filters('karma_mega_menu...', 'karma_walker')
#2 /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/class-wp-hook.php(308): karma_megamenu->modify_arguments(Array)
#3 /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/plugin.php(205): WP_Hook->apply_filters(Array, Array)
#4 /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/nav-menu-template.php(97): apply_filters('wp_nav_menu_arg...', Array)
#5 /usr/home/globenet/domains/wazony24.pl/public_html/wp-content/themes/karma/theme-template-part-horizontal-sub-menu.php(37): wp_nav_menu(Array)
#6 /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/template.php(785): require('/usr/home/globe...')
#7 /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/template.php(718): load_template('/usr/home/globe...', false, Array)
#8 /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/general-template.php(204): locate_template(Array, true, false, Array)
#9 /usr/home/globenet/domains/wazony24.pl/public_html/wp-content/themes/karma/template-portfolio-3-columns.php(68): get_template_part('theme-template-...')
#10 /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/template-loader.php(106): include('/usr/home/globe...')
#11 /usr/home/globenet/domains/wazony24.pl/public_html/wp-blog-header.php(19): require_once('/usr/home/globe...')
#12 /usr/home/globenet/domains/wazony24.pl/public_html/index.php(17): require('/usr/home/globe...')
#13 {main}
thrown in /usr/home/globenet/domains/wazony24.pl/public_html/wp-includes/class-wp-hook.php on line 308
