The error looks something like this (the full path and line number may be different):
Fatal error: Call to undefined method WC_Shipping::get_available_shipping_methods() in .../wp-content/themes/THEME-NAME/woocommerce/checkout/review-order.php on line 14
This issue is caused by your theme, they are bundling outdated template files in their themes that have been deprecated for a while now. You should contact the theme developer to get this fixed properly. You can delete that specific file from your theme until this issue has been patched by your theme developer for a temporary fix. WooCommerce will fall back on the default template file, bundled with the plugin.