Shipping Method Estimator not working with custom address attributes

[SamJUK]

Preconditions (*)

1. Magento 2.3.4 with Sample data
2. A module that declares a custom attribute for as per instructions from dev docs (https://devdocs.magento.com/guides/v2.3/howdoi/checkout/checkout_new_field.html#add)

Steps to reproduce (*)

1. Install a module that adds a custom address attribute (either follow the dev docs to create your own or install the module below)
   1. https://github.com/SamJUK/m2-custom-attribute-bug
2. Enable and Redeploy site
3. Add item to cart and proceed to shipping step of checkout
4. Fill out shipping information (custom attribute + address data)
5. Select a shipping rate
6. Navigate back to your cart
7. Trigger a estimate shipping event
   1. Either try to use shipping estimator on the cart with a new postcode
   2. Or continue back to checkout and change postcode

Expected result (*)

1. Pull through shipping rates for the new postcode

Actual result (*)

1. https://www.youtube.com/watch?v=cy3gQqQZ0fs
2. Estimate shipping methods request returns a 400 bad request with the following error message
   {"message":"Error occurred during \"custom_attributes\" processing. A custom attribute is specified with a missing attribute code. Verify the code and try again."}

Due to strange nesting within the custom_attribute property. Originally while its working the address payload is of the following format

custom_attributes: [{
    "attribute_code": "custom_field", 
    "value": "123" 
}]

Where was when we are getting 400 errors the custom attributes looks like so

custom_attributes: [{
    "attribute_code": "0", 
    "value": {
        "attribute_code": "custom_field", 
        "value": "123" 
    }
}]

Currently using the following Hotfix to allow for checkout
https://gist.github.com/SamJUK/479ca3f108b8091fbf512695f97363fb

Additional information

#27505 (comment)

[m2-assistant]

Hi @SamJUK. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

• Summary of the issue
• Information on your environment
• Steps to reproduce
• Expected and actual results

Please make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, please, add a comment to the issue:

@magento give me 2.4-develop instance - upcoming 2.4.x release

For more details, please, review the Magento Contributor Assistant documentation.

@SamJUK do you confirm that you were able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

---

• Join Magento Community Engineering Slack and ask your questions in #github channel.

[vipin12117]

I am also facing same issue. Is magento confirmed issue and fixing it ?

[sdzhepa]

Can confirm this issue and additional want to add it can be easily reproduced on EE editions.
In EE Edition there is UI to create/edit Customer address Attributes
So it can prove that issue in Magento but not in test-module or DevDoc

Case for EE:

1. In Admin go to Stores > Customer Address Attributes
2. create New Customer Address Attributes e.g. with this configuration https://www.screencast.com/t/DrIdq7GLy
3. Go to Storefront and add a simple product to the cart
4. Go to Shopping Cart and open "Estimate Shipping and Tax"
5. Fill some valid data e.g.

• Country = United States
• State/Province = Texas
• ZIP = 78681

RESULT - OK:

• no errors
• Shipping method is available
• https://www.screencast.com/t/lizz2qHszrc

6. Now go to Checkout
7. Fill Custom Attribute value e.g. "qwe"
8. Fill other required fields with a valid date
9. Go back to the shopping cart page
10. open "Estimate Shipping and Tax"
11. Change Zip, e.g. ZIP = 78682
12. Change zip again to ZIP = 78681

RESULT- NOT OK:

• shipping is not available
• error {code}Error occurred during "custom_attributes" processing. A custom attribute is specified with a missing attribute code. Verify the code and try again."{code}
• https://www.screencast.com/t/IEXgi9Inl

[magento-engcom-team]

✅ Confirmed by @sdzhepa
Thank you for verifying the issue. Based on the provided information internal tickets MC-34264 were created

Issue Available: @sdzhepa, You will be automatically unassigned. Contributors/Maintainers can claim this issue to continue. To reclaim and continue work, reassign the ticket to yourself.