I’m trying to create a custom User Registration form on a WordPress theme. I made a plugin where I’ve added my desired fields and save those fields with some hooks.

All of it works fine except for when I try to include the profile_update hook, then I get a out of memory error. I assume something ain’t right here so here’s the code

    add_action('woocommerce_register_form_start', 'front_end_field');

function front_end_field()
{
?>
    <p class="form-row form-row-first">
        <label for="billing_first_name"><?php _e('First name', 'text_domain'); ?><span class="required">*</span></label>
        <input required type="text" class="input-text" name="billing_first_name" id="billing_first_name" value="<?php if (!empty($_POST['billing_first_name'])) esc_attr_e($_POST['billing_first_name']); ?>" />
    </p>
....

add_action('woocommerce_register_post', 'validate_input', 3, 10);

function validate_input($username, $email, $validation_errors)
{
    if (isset($_POST['billing_first_name']) && empty($_POST['billing_first_name'])) {
        $validation_errors->add('billing_first_name_error', __('<strong>Error</strong>: First name is required!', 'text_domain'));
    }
.....


function save_data($customer_id)
{
    if (isset($_POST['billing_first_name'])) {
        update_user_meta($customer_id, 'first_name', sanitize_text_field($_POST['billing_first_name']));
        update_user_meta($customer_id, 'billing_first_name', sanitize_text_field($_POST['billing_first_name']));
... 


// Error starts below 
    add_action( 'profile_update', 'my_profile_update', 10, 2 ); // Causes Site to Crash (Max out memeory)

function my_profile_update( $user_id, $old_user_data ) {

    if (isset($_POST['user_url'])) {
        wp_update_user( array( 'ID' => $user_id, 'user_url' =>  sanitize_text_field($_POST['user_url']) ) );
    }

}

>Solution :

profile_update hook is triggered again when you update the user causing an infinite loop, you can prevent this by removing the hook before updating like this

add_action( 'profile_update', 'my_profile_update', 10, 2 ); // Causes Site to Crash (Max out memeory)

function my_profile_update( $user_id, $old_user_data ) {
    remove_action( 'profile_update', 'my_profile_update', 10 );
    if (isset($_POST['user_url'])) {
        wp_update_user( array( 'ID' => $user_id, 'user_url' =>  sanitize_text_field($_POST['user_url']) ) );
    }
    add_action( 'profile_update', 'my_profile_update', 10, 2 );

}