[UI-Extensions]: useApplyCartLinesChange hook triggers contact and zipcode form validlation

Topic summary

Issue: Adding a cart line during checkout via the Shopify UI Extensions hook useApplyCartLinesChange triggers checkout form validation, showing errors for missing contact information and zipcode before the customer enters any data.

Context: This behavior is new (worked fine a few weeks ago) and is suspected to be caused by the useApplyCartLinesChange hook, which applies changes to cart line items. Multiple developers have reported the same problem. An attached screenshot illustrates the validation errors but is not essential to understand the issue.

Request: A bug fix or a workaround was requested.

Latest update: A responder advised tracking progress on GitHub issue #2069 (https://github.com/Shopify/ui-extensions/issues/2069). No workaround or fix was provided in the thread.

Status: Unresolved and ongoing; awaiting updates via the linked GitHub issue.

Summarized with AI on December 25. AI used: gpt-5.

When a cart line item is added to the cart during checkout, form validation is triggered, and users are presented with validation errors indicating that contact information or zipcode is missing. This just started happening recently; it was working perfectly fine a few weeks ago.
And this is unexpected from my perspective, as the customer has not provided any input.

The validation is likely trigged by the call of the useApplyCartLinesChange hook. I have noticed that other developers are also facing the same issue and have raised tickets on GitHub, but unfortunately, there has been no update or response.

Dear Team, could you kindly resolve this bug or suggest a potential solution for this issue?

Hi Quentin,

Your best option would be to follow this GitHub issue for an update on this: https://github.com/Shopify/ui-extensions/issues/2069