Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, function "change_existing_currency_symbol" not found or invalid function name in /home/olympiad/public_html/wp-includes/class-wp-hook.php:324 Stack trace: #0 /home/olympiad/public_html/wp-includes/plugin.php(205): WP_Hook->apply_filters('د.ا', Array) #1 /home/olympiad/public_html/wp-content/plugins/woocommerce/includes/wc-core-functions.php(854): apply_filters('woocommerce_cur...', 'د.ا', 'JOD') #2 /home/olympiad/public_html/wp-content/plugins/woocommerce/includes/widgets/class-wc-widget-price-filter.php(45): get_woocommerce_currency_symbol() #3 /home/olympiad/public_html/wp-includes/class-wp-widget-factory.php(62): WC_Widget_Price_Filter->__construct() #4 /home/olympiad/public_html/wp-includes/widgets.php(115): WP_Widget_Factory->register('WC_Widget_Price...') #5 /home/olympiad/public_html/wp-content/plugins/woocommerce/includes/wc-widget-functions.php(39): register_widget('WC_Widget_Price...') #6 /home/olympiad/public_html/wp-includes/class-wp-hook.php(324): wc_register_widgets('') #7 /home/olympiad/public_html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array) #8 /home/olympiad/public_html/wp-includes/plugin.php(517): WP_Hook->do_action(Array) #9 /home/olympiad/public_html/wp-includes/widgets.php(1862): do_action('widgets_init') #10 /home/olympiad/public_html/wp-includes/class-wp-hook.php(324): wp_widgets_init('') #11 /home/olympiad/public_html/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array) #12 /home/olympiad/public_html/wp-includes/plugin.php(517): WP_Hook->do_action(Array) #13 /home/olympiad/public_html/wp-settings.php(695): do_action('init') #14 /home/olympiad/public_html/wp-config.php(94): require_once('/home/olympiad/...') #15 /home/olympiad/public_html/wp-load.php(50): require_once('/home/olympiad/...') #16 /home/olympiad/public_html/wp-blog-header.php(13): require_once('/home/olympiad/...') #17 /home/olympiad/public_html/index.php(17): require('/home/olympiad/...') #18 {main} thrown in /home/olympiad/public_html/wp-includes/class-wp-hook.php on line 324