Add To Cart and Checkout Sometimes Not Working While Preload Links enabled

[joejoe04]

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Describe the bug When adding an item to the WooCommerce cart and then proceeding to checkout, the item added is no longer in the cart for checkout.

The user reports it must be an item you've not added before, and also that the issue only occurs sporadically.

Ahmed has already done some testing this and found that disabling the Enable Link Preloading is disabled, the issue no longer happens.

To Reproduce Steps to reproduce the behavior:

1. Make sure Enable Link Preloading option is enabled
2. Go to a page like https://ueliexpress.ch/ueliestage/produkt-kategorie/apple-zubehoer/ (staging site is being used for testing because WP Rocket is disabled on production)
3. Hover over an item and click the cart icon to add to cart
4. Click 'KASSE' to go to check out
5. It doesn't happen every time, but when it does, you will be taken to a checkout page saying there are no items in the cart

Expected behavior The checkout process should work normally with all the items a person has added.

Active Theme Woodmart

Active Plugins 301 Redirects Pro ATUM Inventory Management for WooCommerce Barcode Label Printing for WooCommerce and others plugins - (basic) Classic Widgets Coinbase Commerce For WooCommerce Contact Form 7 Converter for Media Customer Reviews for WooCommerce Customer Reviews for WooCommerce PRO Disable Cart Fragments Fraud Prevention For Woocommerce GA Google Analytics GTranslate Loco Translate mame TWINT for WooCommerce mame WebStamp for WooCommerce PDF Invoices & Packing Slips for WooCommerce PixelYourSite PRO PixelYourSite Super Pack Product Feed PRO for WooCommerce Purchased Items Column WooCommerce Really Simple SSL Really Simple SSL Pro reCAPTCHA for WooCommerce Slider Revolution Slider Revolution Bubblemorph AddOn Slider Revolution Mousetrap Add-On Slider Revolution Transitionpack Add-On UpdraftPlus - Backup/Restore WooCommerce WooCommerce Extra Fees Plugin WooCommerce Orders & Customer exporter WooCommerce PayPal Payments WooCommerce Stripe Gateway Woodmart Core Wordfence Security WP Downgrade | Specific Core Version WP File Manager WP Rocket WP Rocket | Deactivate WooCommerce Refresh Cart Fragments Cache WP Rollback WPBakery Page Builder Yoast SEO Yoast SEO Premium Yoast SEO: WooCommerce

Additional context https://secure.helpscout.net/conversation/2160191527/401959/ https://wp-media.slack.com/archives/C43T1AYMQ/p1680589677084819 https://wp-media.slack.com/archives/C43T1AYMQ/p1681465535232939 https://wp-media.slack.com/archives/C43T1AYMQ/p1681998798196959

Backlog Grooming (for WP Media dev team use only)

• [ ] Reproduce the problem
• [ ] Identify the root cause
• [ ] Scope a solution
• [ ] Estimate the effort

[piotrbak]

Acceptance Criteria

• Cart - Checkout relation should be working correctly in all cases when using Preload Links feature
• Preload Links feature should be able to exclude URLs without regression and don't preload
• Preload Links feature should not preload Never Cached URLs and specific extensions

[joejoe04]

User wrote back to let us know they needed to delete the staging site, but they also confirmed that the issue was resolved for them while the Preload Links option is disabled.

[piotrbak]

We did not have any feedback from customers about this issue.