Fatal error Allowed memory size exhausted with WooCommerce WordPress plugin

Find the default-constants.php file on wordpress\wp-includes folder.
Try changing line 23 :

define('WP_MEMORY_LIMIT', '40M');  

to :

define('WP_MEMORY_LIMIT', '128M');

Are you using WooCommerce Tickets plugin by Modern Tribe? If so, then you need to download the latest version (3.9.2) and install that. (You'll likely need to deactivate and delete the old version). For some reason it's not giving alert that an upgrade is available.

I had tried everything suggested on other forums and finally found this solution and it was the only thing to solve my problem. Hope it helps you!

Maybe you have the bad hook. look at this exemple : i had the same error before

Allowed memory size of 1317011456 bytes exhausted (tried to allocate 262144 bytes) in /home/mala4322/antivirusedition.nash-project.name/wp-content/plugins/woocommerce/includes/class-wc-cart.php on line 623

I changet add_action( 'woocommerce_cart_updated', [$this, 'sauver_champs_perso_panier'] ); for        add_action( 'woocommerce_update_cart_action_cart_updated', [$this, 'sauver_champs_perso_panier'] );
and it was solved

 public function __construct() {

         // Lors du UPDATE CART → on ajoute les données
       add_action( 'woocommerce_update_cart_action_cart_updated', [$this, 'sauver_champs_perso_panier'] );

        // Réafficher dans le panier
        add_filter( 'woocommerce_get_item_data', [$this, 'afficher_donnees_panier'], 10, 2 );

        // Sauvegarde dans la commande lors du checkout
       // add_action( 'woocommerce_checkout_create_order_line_item', [$this, 'sauver_donnees_dans_commande'], 10, 4 );

       
       // add_action( 'woocommerce_update_cart_action_cart_updated', [$this, 'save_custom_cart_item_data']);


    }


    /**
     * Sauvegarde des champs quand l'utilisateur clique "Update Cart"
     */
    function sauver_champs_perso_panier() {
        
        foreach ( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {

            // Durée perso
            if ( isset($_POST['alm_duree'][$cart_item_key]) ) {
                $duree = sanitize_text_field( $_POST['alm_duree'][$cart_item_key] );
                WC()->cart->cart_contents[$cart_item_key]['alm_duree'] = $duree;
            }

            // Client perso
            if ( isset($_POST['alm_client'][$cart_item_key]) ) {
                $client_id = intval($_POST['alm_client'][$cart_item_key]);
                WC()->cart->cart_contents[$cart_item_key]['alm_client'] = $client_id;
            }
        }

        WC()->cart->set_session();
    }