This article covers Shopify error 429 too many requests. Basically, 429 too many requests can trigger due to increased number of API requests.
Calls to the REST Admin API are governed by request-based limits, which means you should consider the total number of API calls your app makes.
In addition, there are resource-based rate limits and throttles.
To avoid rate limit errors in Shopify:
Designing your app with best practices in mind is the best way to avoid throttling errors.
1. Optimize your code to only get the data that your app requires.
2. Use caching for data that your app uses often.
3. Regulate the rate of your requests for smoother distribution.
4. Include code that catches errors. If you ignore these errors and keep trying to make requests, then your app won’t be able to gracefully recover.
5. Use metadata about your app's API usage, included with all API responses, to manage your app’s behavior dynamically.
6. Your code should stop making additional API requests until enough time has passed to retry.
The recommended backoff time is 1 second.