To minimize barriers to purchase, you enable guest checkout so users can buy items without registering an account. However, an authentication bug causes checkout forms to fail for specific users. A customer fills out their billing details, checks out as a guest, but the page returns an error stating: "An account is already registered with your email address. Please log in." This completely defeats the purpose of guest checkouts. If the customer can't remember their password, they are trapped in a loop and will likely abandon their cart. This logic bug occurs when WooCommerce configurations are set to automatically generate accounts in the background based on billing emails, but the validation system encounters a hard conflict with pre-existing account records in the wp_users database table.

The Solution

Resolving account conflicts requires adjusting checkout account creation behavior or gracefully bypassing rigid account checks for guest purchases.

  1. Adjust Account Privacy Settings: Go to WooCommerce > Settings > Accounts & Privacy. Under the Guest checkout block, verify that Allow customers to place orders without an account is explicitly checked.

  2. Deactivate Forced Creation Rules: On that same settings page, uncheck the box labeled "When creating an account, automatically generate an account username based on the name, surname or email". This prevents automated collisions.

  3. Implement Graceful Guest Routing: Add this custom filter function to your store setup to allow the checkout script to complete smoothly under an unlinked, decoupled guest order mapping layout, rather than throwing hard account blocks:

PHP
 
add_filter('woocommerce_checkout_posted_data', 'bypass_strict_email_account_collision', 10, 1);
function bypass_strict_email_account_collision($data) {
    if (!is_user_logged_in() && email_exists($data['billing_email'])) {
        // Temporarily overrides the creation flag to ensure order completes cleanly as a guest
        add_filter('woocommerce_checkout_registration_enabled', '__return_false', 99);
    }
    return $data;
}