Shopify Functions WASM build failing — or Partner deploy rejects the artifact before checkout ever runs.

Several Shopify Functions products can look like “Functions are broken.” They do not share a fix. This page is only when the WASM artifact never builds, or Partner Dashboard rejects the Function release before buyers hit checkout. Discount Function combinesWith / stacking wrong at checkout is shopify-discount-function-not-stacking. Delivery customization rename/hide/reorder failing on live rates is shopify-delivery-customization-function-failing. Payment customization not hiding or reordering gateways is shopify-payment-customization-not-hiding. Cart Transform not applying bundles/line merges is shopify-cart-transform-function-broken. Checkout validation rejecting valid carts at runtime is shopify-checkout-validation-function-blocking.

Six ordinary reasons WASM never lands: wrong or missing wasm32 / WASI target for your Rust or JS toolchain, Shopify CLI / Function API version mismatch, GraphQL input query / schema generate out of date, shopify.extension.toml type/api_version/handle typo, Javy or binary size limits failing Create version, or you are debugging a live checkout Function outcome and calling it a build failure.

Reproduce locally with the same CLI your CI uses: shopify app function build (or language-native cargo build / npm run build for the Function package). Save the full stderr — missing target, schema generate errors, TypeScript/Rust type failures, Javy not found. Confirm whether a .wasm file appears under the extension build directory.

In Partner Dashboard → your app → Extensions / Versions, try Create version / Release. Note whether the failure is “invalid Function artifact,” size/limit, API version, or whether the version creates but Activate never marks the Function Active on the development store. If the Function is Active and checkout behavior is wrong, stop — that is a runtime playbook, not this page.

Capture: Shopify CLI version, Function API version in shopify.extension.toml, language (Rust vs JS), target triple, schema generate command output, path to the .wasm (or proof it is missing), and the exact Partner error string. Soft-link Scripts → Functions migration when the product is retiring Script Editor rather than compiling WASM.

Install the documented Shopify Functions toolchain for your API version (Rust wasm target / JS Javy path as Shopify currently documents). Align Shopify CLI, app template, and Function extension versions. Regenerate the Function input query / schema from GraphQL after API bumps. Fix typos in type, api_version, and handle inside shopify.extension.toml.

Rebuild until a valid .wasm exists. Push the app / create a new version / release to the development store. Confirm the Function shows Active (not Draft / failed). Only then run a buyer checkout to see runtime behavior — and if runtime is wrong, branch to the matching Function-type playbook below.

Soft notes after a clean WASM release: discount stacking; delivery customization; payment customization; cart transform; checkout validation. Scripts retirement is shopify-scripts-to-functions-migration.

Discount Function / automatic discounts not stacking is shopify-discount-function-not-stacking. Delivery Customization Function failing is shopify-delivery-customization-function-failing. Payment Customization not hiding gateways is shopify-payment-customization-not-hiding. Cart Transform Function broken is shopify-cart-transform-function-broken. Checkout validation Function blocking is shopify-checkout-validation-function-blocking.

The only honest test for this page: local build produces a .wasm, Partner Create version / Release succeeds, Function status is Active on the store, and only then do you evaluate checkout. Anything else after Active is a different product.

Stay DIY if you can spend one afternoon on the list above: fix the wasm target / CLI / schema / extension.toml, rebuild until a .wasm exists, release in Partner Dashboard, confirm Active, then retest. That is the whole playbook. No agency required. Short answers also live on the merchant FAQ. Related pages: discount Function, delivery customization, payment customization, cart transform, checkout validation.

Pay for help when the work is not the compiler error — it is connecting the stack you already have so lead capture is not dying in DMs, storefront and checkout-ready exceptions land in a channel you already check, and the live store is one workflow instead of a spreadsheet plus a Slack bot you forgot. That is the Latch AI Ops install.

What $997 USD one-time buys: lead capture on the live store, ops alerts in a channel you already check, and a checkout-ready workflow. 72 hours after collaborator access, not after payment. One live Shopify store. Access plus a delivery thread. Store URL collected at checkout. Not a SaaS seat, not a theme rebuild retainer, not a conversion guarantee, not a brand or theme job.

Other shops’ public ranges, not testimonials: a checkout / ops install typically runs $500–$2,500. A full ops consulting block typically runs $2,000–$5,000. $997 is the cheap end of that work, sold as a 72-hour install of three systems — not as an earnings number or conversion-lift claim.

What it does not buy: more orders, recovered revenue, a forever Functions uptime guarantee, or a case study. Latch AI Ops has not published customer proof because there are no customers yet. You are buying the install.

Checkout is on Whop. Operator is Nico. United States offer. You can revoke collaborator access after handoff. We do not take owner passwords.