WooCommerce: Fixing Fatal error Call to undefined function wc_get_order()

I developed a custom payment gateway plugin for a client, who wanted to add a similar method to “cod” (cash on delivery). FYI, he wanted to add a method called “card on delivery”. I simply duplicated the code, added the PHP to a file, made a plugin and gave him the plugin zip file. And everything was working great… until he did a test checkout.

The error that showed after placing an order

Fatal error: Call to undefined function wc_get_order() in /home/XXXXXXX/public_html/wp-content/plugins/woocommerce-gateway-carddelivery-plugin/woocommerce-gateway-carddelivery-plugin.php on line 201

The fix: wc_get_order() is only valid for WooCommerce 2.2+

It was very simple. The client was still using WooCommerce 2.1, where new orders are called differently. From WooCommerce 2.2, orders are created with wc_get_order() instead.

I simply substituted this:

$order = wc_get_order( $order_id );

with this:

$order = new WC_Order( $order_id );

Where to add custom code?

You should place PHP snippets at the bottom of your child theme functions.php file and CSS at the bottom of its style.css file. Make sure you know what you are doing when editing such files - if you need more guidance, please take a look at my guide "Should I Add Custom Code Via WP Editor, FTP or Code Snippets?" and my video tutorial "Where to Place WooCommerce Customization?"

Does this snippet (still) work?

Please let me know in the comments if everything went as expected. I would be happy to revise the snippet if you report otherwise (please provide screenshots). I have tested this code with Storefront theme, the WooCommerce version listed above and a WordPress-friendly hosting.

If you think this code saved you time & money, feel free to join 17,000+ WooCommerce Weekly subscribers for blog post updates and 250+ Business Bloomer supporters for 365 days of WooCommerce benefits. Thank you in advance!

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Rodolfo Melogli

Business Bloomer Founder

Author, WooCommerce expert and WordCamp speaker, Rodolfo has worked as an independent WooCommerce freelancer since 2011. His goal is to help entrepreneurs and developers overcome their WooCommerce nightmares. Rodolfo loves travelling, chasing tennis & soccer balls and, of course, wood fired oven pizza.

10 thoughts on “WooCommerce: Fixing Fatal error Call to undefined function wc_get_order()

  1. I have same issue, but I the issue when I use the function wc_get_orders()
    Its when I use it inside “my custom function” plugin
    (which I think is just appending to the main functions php file)

    How can I fix that?
    Do I need to include the wc-order-functions.php file before calling wc_get_orders() or how do I fix it ?
    require_once( dirname( __FILE__ ) . ‘/includes/wc-order-functions.php’ );

    Thank You 🙂

    1. Hi Michael, thanks so much for your comment! Yes, this is possible – unfortunately this is custom work and I cannot provide a complementary solution here via the blog comments. Thanks a lot for your understanding! ~R

  2. Thank you! This saved me who-knows-how-much time!
    I was getting a slightly different Fatal Error:
    Uncaught Error: Call to undefined method WC_Order_Refund::get_billing_first_name()

    But this still did the trick!

    1. Awesome!

      1. I’m getting Error thrown: Call to undefined method WC_Order::get_billing_first_name() and can’t get it fixed. Any thoughts on this?

        1. Hello JV, thanks so much for your comment! Yes, this is definitely possible, but I’m afraid it’s custom work. If you’d like to get a quote, feel free to contact me here. Thanks a lot for your understanding!

  3. Hi, could you guide me with this error:

     1=""to"" 2=""undefined"" 3=""function"" 4=""wcs_order_contains_renewal()"" 5=""in"" 6=""/home/xxxxx/domains/xxx.xx/public_html/onlinelearning/wp-content/plugins/ld-group-registration/modules/class-wdm-woocommerce.php"" 7=""on"" 8=""line"" 9=""137"" 10=""
    1. Fred, thanks for your comment! I recommend to talk to the “ld-group-registration” plugin devs 🙂

  4. Minha página principal apresenta o seguinte erro:
    Fatal error: Call to undefined function woocommerce_reset_loop() in /home2/tapetesc/public_html/wp-content/themes/mrtailor/inc/shortcodes/product-categories.php on line 116

    Como posso resolver esse problema?

    1. Thanks for your message Camila. Did this error appear after you tried using my function?

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