I tested the payment flow from a product page, and it worked correctly on your site. Could you please provide the exact steps required to reproduce the issue?
If you can reproduce it consistently, please perform a conflict test on a staging site:
Temporarily switch to the default Storefront theme.
Deactivate all plugins except WooCommerce and WooCommerce PayPal Payments.
Repeat the same payment flow.
If the error disappears, reactivate the theme and plugins individually, testing after each activation to identify the conflict.
If the issue persists with only WooCommerce and PayPal Payments active, please let us know, however its likely a classic type of conflict.
I have already tested the issue by deactivating all plugins and switching to the default theme, but the problem still persists. Because of this issue, users are unable to create orders.
I found the following errors in the error logs:2026-08-14T02:35:03+00:00 Debug #5948 - [New Request] POST / 2026-08-14T02:35:03+00:00 Error #5948 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:35:03+00:00 Error #5948 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:38:13+00:00 Debug #1858 - [New Request] POST / 2026-08-14T02:38:13+00:00 Error #1858 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:38:13+00:00 Error #1858 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:38:16+00:00 Debug #6651 - [New Request] POST / 2026-08-14T02:38:16+00:00 Error #6651 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:38:16+00:00 Error #6651 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:38:50+00:00 Debug #3872 - [New Request] POST / 2026-08-14T02:38:50+00:00 Error #3872 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:38:50+00:00 Error #3872 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:38:54+00:00 Debug #4755 - [New Request] POST / 2026-08-14T02:38:54+00:00 Error #4755 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:38:54+00:00 Error #4755 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:40:22+00:00 Debug #7541 - [New Request] POST / 2026-08-14T02:40:22+00:00 Error #7541 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:40:22+00:00 Error #7541 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:40:26+00:00 Debug #1153 - [New Request] POST / 2026-08-14T02:40:26+00:00 Error #1153 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:40:26+00:00 Error #1153 - Cart simulation failed: Error adding products to cart. 2026-08-14T02:41:58+00:00 Debug #6962 - [New Request] GET /product/kafka/
I also tested the site in incognito mode, and the following error appears in the browser console on the product page:ppcp-button-js-butto…js?ver=1786700918:1 Uncaught (in promise) {name: '', message: 'Error adding products to cart.', code: 0, details: Array(0)} (anonymous)@ppcp-button-js-butto…js?ver=1786700918:1 Promise.then(anonymous)@ppcp-button-js-butto…js?ver=1786700918:1 value@ppcp-button-js-butto…js?ver=1786700918:1 value@ppcp-button-js-butto…js?ver=1786700918:1 i@ppcp-button-js-butto…js?ver=1786700918:1 (anonymous)@ppcp-button-js-butto…js?ver=1786700918:1 value@ppcp-button-js-butto…js?ver=1786700918:1 value@ppcp-button-js-butto…js?ver=1786700918:1 value@ppcp-button-js-butto…js?ver=1786700918:1 (anonymous)@ppcp-button-js-butto…js?ver=1786700918:1 (anonymous)@ppcp-button-js-butto…js?ver=1786700918:1 Promise.then vt@ppcp-button-js-butto…js?ver=1786700918:1 (anonymous)@ppcp-button-js-butto…js?ver=1786700918:1 T@tabba-85-midi-length…ed-poly-duchesse/:3 await in Tt@tabba-85-midi-length…ed-poly-duchesse/:3 await in trun@tabba-85-midi-length…ed-poly-duchesse/:3 (anonymous)@tabba-85-midi-length…ed-poly-duchesse/:3 (anonymous)@tabba-85-midi-length…ed-poly-duchesse/:3
When I go to the checkout page, I get another JavaScript error:ppcp-axo-js-boot.js?ver=4.1.2:1 Uncaught TypeError: Cannot read properties of null (reading 'insertAdjacentHTML') at e.value (ppcp-axo-js-boot.js?ver=4.1.2:1:49098) at e.value (ppcp-axo-js-boot.js?ver=4.1.2:1:48303) at HTMLInputElement.<anonymous> (ppcp-axo-js-boot.js?ver=4.1.2:1:43090) at HTMLDocument.dispatch (jquery.min.js?ver=3.7.1:2:40035) at v.handle (jquery.min.js?ver=3.7.1:2:38006) at Object.trigger (jquery.min.js?ver=3.7.1:2:70124) at HTMLInputElement.<anonymous> (jquery.min.js?ver=3.7.1:2:70701) at ce.each (jquery.min.js?ver=3.7.1:2:3129) at ce.fn.init.each (jquery.min.js?ver=3.7.1:2:1594) at ce.fn.init.trigger (jquery.min.js?ver=3.7.1:2:70701)
The errors appear to be related to the PayPal Checkout/PayPal Complete Payments scripts (ppcp-button and ppcp-axo).
Could you please investigate this issue and determine why the cart simulation is failing and why the PayPal scripts are throwing these JavaScript errors?
I have also recorded a video showing the issue here:
However, this may only suppress the simulation and is unlikely to resolve an underlying product configuration issue. The additional AXO error is unrelated and can be ignored at this point. I am happy to investigate this directly. Please open a ticket through our Request Support page and include this thread URL.
