Fatal error: Call to undefined method WooCommerce::nonce_field()

by

The Products section in wp-admin panel doesn’t depend on the theme. If you select default WordPress theme you’ll see the same issue. This is WordPress configuration.
To fix the errors you need edit files via FTP, open the file wp-content/themes/your_theme/woocommerce/cart/shipping-calculator.php on line 67 and replace

$woocommerce->nonce_field

     with

  wp_nonce_field

and the file wp-content/themes/your_theme/woocommerce/checkout/form-checkout.php on line 3 and replace

 $woocommerce->show_messages();

      with

  wc_print_notices();