Title: Bug: is_checkout() function error
Last modified: September 11, 2026

---

# Bug: is_checkout() function error

 *  Resolved [Pieter Sand](https://wordpress.org/support/users/beachholiday/)
 * (@beachholiday)
 * [2 weeks, 3 days ago](https://wordpress.org/support/topic/bug-is_checkout-function-error-2/)
 * Dear Support,
   We are experiencing an intermittent issue on our website.
 * On September 9, 2026, the /feed/ URL returned a 500 error with the following 
   message:
   Call to undefined function PaymentPlugins\Stripe\is_checkout()
 * My hosting provider confirmed that the is_checkout() function exists in WooCommerce
   11.1.0, but it was not available during the affected request. They also found
   several other WooCommerce file-loading errors in the server logs around the same
   period, including an instance where a required WooCommerce file could not be 
   loaded.
 * Could you please investigate whether this is an issue that can be addressed on
   your end, or advise if there is anything I should check on my side to help prevent
   it from happening again?
 * The error appears to occur intermittently and is not present on every request,
   based on the server logs.
   WooCommerce: 11.1.0WooCommerce Stripe Payment: 4.0.13
 * We posted this support request in the WooCommerce forum but were requested to
   post it again here:
   [https://wordpress.org/support/topic/bug-is_checkout-function-error/](https://wordpress.org/support/topic/bug-is_checkout-function-error/)
 * Many thanks for your help with this.
 * Piet

Viewing 1 replies (of 1 total)

 *  Plugin Support [shahzeen(woo-hc)](https://wordpress.org/support/users/shahzeenfarooq/)
 * (@shahzeenfarooq)
 * [2 weeks, 3 days ago](https://wordpress.org/support/topic/bug-is_checkout-function-error-2/#post-19017639)
 * Hi [@beachholiday](https://wordpress.org/support/users/beachholiday/)!
 * Thank you for providing the details and for sharing the error message and plugin
   versions. I understand that the issue is intermittent and that the `is_checkout()`
   function is sometimes unavailable when the `/feed/` URL is accessed.
 * I’m also sorry that you were previously directed to create a thread in the wrong
   forum.
 * From the error you shared, the issue appears to be related to Payment Plugins
   for Stripe WooCommerce, which is a third-party Stripe integration. Since you 
   are using that plugin, please create a support thread with their developers here:
 * [https://wordpress.org/support/plugin/woo-stripe-payment/](https://wordpress.org/support/plugin/woo-stripe-payment/)
 * Please note that this forum provides support for our official WooCommerce Stripe
   Gateway plugin:
 * [https://wordpress.org/plugins/woocommerce-gateway-stripe/](https://wordpress.org/plugins/woocommerce-gateway-stripe/)
 * As the error specifically references the `PaymentPlugins\Stripe` namespace, the
   developers of Payment Plugins for Stripe WooCommerce will be best placed to investigate
   why `is_checkout()` was unavailable during the affected request and advise on
   the intermittent file-loading issue.
 * I hope this clarifies where you should post the issue for further investigation.
   Sorry again for the confusion, and thank you for your understanding.

Viewing 1 replies (of 1 total)

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 * 1 reply
 * 2 participants
 * Last reply from: [shahzeen(woo-hc)](https://wordpress.org/support/users/shahzeenfarooq/)
 * Last activity: [2 weeks, 3 days ago](https://wordpress.org/support/topic/bug-is_checkout-function-error-2/#post-19017639)
 * Status: resolved