Title: JS Error on Checkout Last modified: August 23, 2019 --- # JS Error on Checkout * Resolved [Chris Raymond](https://wordpress.org/support/users/chrisraymond/) * (@chrisraymond) * [6 years, 8 months ago](https://wordpress.org/support/topic/js-error-on-checkout/) * Hello, Recently started having issues with the checkout page. My team reviewed and appears to be JS issues(Uncaught ReferenceError: WC_Square_Payment_Form_Handler is not defined) which means this class(WC_Square_Payment_Form_Handler) is not available in DOM. Not sure how to resolve as the JS file in in min form. Any ideas how to fix? Thanks in advance. * The page I need help with: _[[log in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fjs-error-on-checkout%2F%3Foutput_format%3Dmd&locale=en_US) to see the link]_ Viewing 7 replies - 1 through 7 (of 7 total) * [Thomas Shellberg](https://wordpress.org/support/users/shellbeezy/) * (@shellbeezy) * Automattic Happiness Engineer * [6 years, 8 months ago](https://wordpress.org/support/topic/js-error-on-checkout/#post-11861180) * Hey [@chrisraymond](https://wordpress.org/support/users/chrisraymond/), * I can see the error in the console on the site but I’m not having that problem on my test site. Are you running version 2.0.3? * I’d try deleting and reinstalling the plugin and retesting. * Thread Starter [Chris Raymond](https://wordpress.org/support/users/chrisraymond/) * (@chrisraymond) * [6 years, 8 months ago](https://wordpress.org/support/topic/js-error-on-checkout/#post-11861208) * Hi [@shellbeezy](https://wordpress.org/support/users/shellbeezy/) We are indeed running version 2.0.3 of this plugin. Also using the latest version of Woocommerce, and WordPress as well. * Thread Starter [Chris Raymond](https://wordpress.org/support/users/chrisraymond/) * (@chrisraymond) * [6 years, 8 months ago](https://wordpress.org/support/topic/js-error-on-checkout/#post-11861233) * Also, tried deleting and reinstalling but issue persists. * [Mike W](https://wordpress.org/support/users/nixiack8/) * (@nixiack8) * [6 years, 8 months ago](https://wordpress.org/support/topic/js-error-on-checkout/#post-11862275) * Hi [@chrisraymond](https://wordpress.org/support/users/chrisraymond/), * Thank you for the additional information! Testing this I too see [the error](https://cld.wthms.co/ffSbQM) on your site. * Checking through my test site, I see some hidden fields but [no errors](https://cld.wthms.co/PIrFxB). Due to this, have you switched out your theme to something like Storefront or Twenty Seventeen temporarily to see if the issue persists? There may be a javascript conflict there that is not happening on our side, which is why we are not able to replicate the issue. * We do recommend a staging site for these tests so that your Live site is unaffected. You can reach out to your Host if you need to have a staging site set up, as they usually can assist you with this. Please let us know the results! * Thread Starter [Chris Raymond](https://wordpress.org/support/users/chrisraymond/) * (@chrisraymond) * [6 years, 8 months ago](https://wordpress.org/support/topic/js-error-on-checkout/#post-11868612) * Hi [@nixiack8](https://wordpress.org/support/users/nixiack8/), Thank you for the recommendation. What we found was custom code in the Functions.php file “ defer js” that caused the issue. Once we removed that, all worked as expected. Thanks. * [jahidulislam](https://wordpress.org/support/users/jahidulislam/) * (@jahidulislam) * [6 years, 4 months ago](https://wordpress.org/support/topic/js-error-on-checkout/#post-12259263) * [@nixiack8](https://wordpress.org/support/users/nixiack8/) [@chrisraymond](https://wordpress.org/support/users/chrisraymond/) Thanks for the help and Post. i also had same problem, it was one of a plugin that having issue. i just deactivated the plugin and worked smoothly. * Anonymous User 18019806 * (@anonymized-18019806) * [5 years, 10 months ago](https://wordpress.org/support/topic/js-error-on-checkout/#post-12988089) * I woke up to this issue on a client site this AM. I found the solution to the issue to be similar to the [@chrisraymond](https://wordpress.org/support/users/chrisraymond/) found. * For me, the issue was the SG Optimizer plugin. I had their “Combine JS Files” feature turned on which was causing this problem. Once I turned that off, the fields loaded just as they should. * Figured I’d add this as this is the top-ranking response for this error on google right now. Viewing 7 replies - 1 through 7 (of 7 total) The topic ‘JS Error on Checkout’ is closed to new replies. * ![](https://ps.w.org/woocommerce-square/assets/icon-256x256.png?rev=3234354) * [WooCommerce Square](https://wordpress.org/plugins/woocommerce-square/) * [Frequently Asked Questions](https://wordpress.org/plugins/woocommerce-square/#faq) * [Support Threads](https://wordpress.org/support/plugin/woocommerce-square/) * [Active Topics](https://wordpress.org/support/plugin/woocommerce-square/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/woocommerce-square/unresolved/) * [Reviews](https://wordpress.org/support/plugin/woocommerce-square/reviews/) * 7 replies * 2 participants * Last reply from: Anonymous User 18019806 * Last activity: [5 years, 10 months ago](https://wordpress.org/support/topic/js-error-on-checkout/#post-12988089) * Status: resolved