Why does my Hydrogen website show a mutation error when trying to add to cart?

[g3misa]

Hi, this just happened about 4 hours ago.  When trying to Add to Cart on my Hydrogen website, this internal error occurs.  My hydrogen version is v2023.7.7.  My node version is v18.17.0.  Thanks in advance.

Error: [h2:error:storefront.mutation] Internal error. Looks like something went wrong on our end.
Request ID: 756e3a8e-0807-44fd-884d-742827eaea62 (include this in support requests). - Request ID: 756e3a8e-0807-44fd-884d-742827eaea62
    at throwError (/node_modules/@shopify/hydrogen/src/storefront.ts:450:5)
    at fetchStorefrontApi (/node_modules/@shopify/hydrogen/src/storefront.ts:339:7)
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at cartCreate (/app/routes/($lang)/cart.tsx:496:24)
    at action (/app/routes/($lang)/cart.tsx:118:18)
    at callRouteActionRR (/node_modules/@remix-run/server-runtime/dist/esm/data.js:31:16)
    at callLoaderOrAction (/node_modules/@remix-run/router/router.ts:3671:16)
    at submit (/node_modules/@remix-run/router/router.ts:2829:16)
    at queryImpl (/node_modules/@remix-run/router/router.ts:2764:22)
    at Object.queryRoute (/node_modules/@remix-run/router/router.ts:2714:18)

[Filiph]

Yeah; mutations have been broken for roughly the same amount of time. Support is no help at all; seems like they haven't been trained at all on how to deal with minor outages or what the storefront API even is. (Interestingly enough though; mutations work fine through the graphiql app; I'm considering just throwing up a hacky solution to "abuse" it for cart mutations in the meanwhile https://shopify-graphiql-app.shopifycloud.com/api/2023-10/graphql)

[g3misa]

Looks like it now forces us to use these types:

node_modules/@shopify/hydrogen/dist/production/index.d.ts 

rather than:

node_modules/@shopify/hydrogen/dist/storefront-api-types.d.ts

I will now need to refactor a LOT of code  😢 

[Filiph]

I'm not using remix/hydrogen, I might hate myself but not enough to use remix. I'm using hydrogen-react with nextjs not that it matters.

Typings would have nothing to do with a backend error, an INTERNAL_SERVER_ERROR (or a 500) is a server error while a 400 would be an error on our end.

AND even if it was on our end you don't just push breaking changes without warning; you deprecate and notify.

[g3misa · Accepted solution]

Was able to fix the issue which was in the Graphql mutation.  For some reason the CartFragment used to work with the merchandise property in the node.  Now that throws an error.    Just had to remove it and make a separate query to get it.   

https://github.com/Shopify/hydrogen/discussions/1561