Imported from jeremylongshore/tons-of-skills-marketplace (
plugins/saas-packs/shopify-pack/skills/shopify-known-pitfalls/SKILL.md). Install upstream withnpx skills add jeremylongshore/tons-of-skills-marketplace --skill shopify-known-pitfalls. Copyright stays with the author (MIT).
Shopify Known Pitfalls
Overview
The 10 most common mistakes when building Shopify apps, with real API examples showing the wrong way and the right way.
Prerequisites
- Existing Shopify app codebase to review or audit
- Familiarity with GraphQL Admin API query patterns and response shapes
- Access scopes configured for the APIs your app uses
@shopify/shopify-apiv9+ installed (for code examples)
Instructions
Each pitfall includes a wrong-way and right-way code example. See Pitfall Examples for all 10 complete code comparisons.
Pitfall #1: Not Checking userErrors (The #1 Mistake)
Shopify GraphQL mutations return HTTP 200 even when they fail. The errors are in userErrors. Always check userErrors.length > 0 before accessing the result.
Pitfall #2: Using REST When GraphQL Is Required
REST Admin API is legacy as of October 2024. New public apps after April 2025 must use GraphQL. GraphQL also lets you request only the fields you need.
Pitfall #3: Ignoring API Version Deprecation
Shopify deprecates API versions ~12 months after release. Use LATEST_API_VERSION from @shopify/shopify-api and monitor x-shopify-api-deprecated-reason response headers.
Pitfall #4: Missing Mandatory GDPR Webhooks
Your app will be rejected from the App Store without customers/data_request, customers/redact, and shop/redact webhook handlers.
Pitfall #5: Webhook Handler Takes Too Long
Shopify expects a 200 response within 5 seconds. Respond immediately and queue work asynchronously, otherwise Shopify retries and creates duplicates.
Pitfall #6: Using ProductInput on API 2024-10+
The ProductInput type was split into ProductCreateInput and ProductUpdateInput in 2024-10. Use the specific type for each operation.
Pitfall #7: Not Using Cursor Pagination
Shopify uses Relay-style cursor pagination, not page numbers. Use after / endCursor with pageInfo.
Pitfall #8: Requesting 250 Items Per Page
first: 250 with nested connections creates enormous query costs that THROTTLE immediately. Use first: 50 or smaller with nested resources.
Pitfall #9: Exposing Admin Token in Client-Side Code
Admin API tokens have full access. Never send them to the browser — proxy through your server.
Pitfall #10: Not Handling APP_UNINSTALLED Webhook
When a merchant uninstalls your app, clean up sessions immediately. Stale sessions cause auth redirect loops on reinstall.
Output
- Anti-patterns identified in codebase
- Fixes prioritized (security first, then correctness)
- Prevention measures in place (linting, CI checks)
Error Handling
| Pitfall | How to Detect | Prevention |
|---|---|---|
| Missing userErrors check | Null pointer crashes | ESLint rule or wrapper function |
| REST usage | grep -r "clients.Rest" src/ |
Migration guide + lint rule |
| Old API version | grep -r "apiVersion" src/ |
CI check against supported versions |
| Missing GDPR webhooks | App Store rejection | Pre-submit compliance checker |
| Webhook timeout | Shopify retry storms | Queue-based processing |
| ProductInput on 2024-10 | GraphQL type error | Update mutations |
| Page-based pagination | Query errors | Use cursor pagination pattern |
first: 250 |
THROTTLED responses | Query cost budgets |
| Admin token in client | Security audit | Server-side proxy |
| No APP_UNINSTALLED | Auth loops on reinstall | Webhook handler + session cleanup |
Examples
Quick Pitfall Scan
Run automated detection against your Shopify codebase to find REST usage, missing userErrors checks, old API versions, hardcoded tokens, and oversized page requests.
See Pitfall Scan Script for the complete scan script.
Resources
- Shopify App Requirements
- GraphQL Migration Guide
- 2024-10 Breaking Changes
- Webhook Best Practices
Quick Reference Card
| Pitfall | Detection | Fix |
|---|---|---|
| No userErrors check | Null crashes on mutations | Always check userErrors.length > 0 |
| REST instead of GraphQL | grep "clients.Rest" |
Migrate to clients.Graphql |
| Old API version | grep "2023-" |
Use LATEST_API_VERSION from SDK |
| Missing GDPR webhooks | App Store rejection | Add 3 mandatory webhook handlers |
| Webhook timeout | Retry storms, duplicates | Respond 200 immediately, queue processing |
| ProductInput on 2024-10 | Type error | Use ProductCreateInput / ProductUpdateInput |
| Page-number pagination | Query errors | Use cursor-based with pageInfo |
first: 250 with nesting |
THROTTLED | Use first: 50 or smaller |
| Admin token in browser | Security scan | Server-side proxy only |
| No APP_UNINSTALLED | Auth loop on reinstall | Clean up sessions on uninstall |