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API New Added 2 October 2026

Stripe: No such customer; a similar object exists in test mode

The ID is real, but it belongs to the other mode. Test and live data in Stripe are entirely separate, so an ID saved during testing cannot be used with a live key. This usually appears straight after going live, when the database still holds customer or price IDs created against the test key.

Quick fix

Read the commands before running them. Anything that restarts a service, deletes data or changes permissions should be tried on a non-production system first.

Quick fix
# Which mode is the key? sk_test_ or sk_live_
echo "${STRIPE_SECRET_KEY:0:8}"

# Look the object up in each mode
stripe customers retrieve cus_123 --api-key "$STRIPE_TEST_KEY"
stripe customers retrieve cus_123 --live

# Store the mode next to every saved Stripe ID, or keep
# separate databases per environment

# Recreate live objects (prices, products, customers) rather than
# copying test IDs across

How to diagnose API errors

API integration errors are usually a contract mismatch: the client and the server disagree about authentication, encoding, size limits, or which version of the API is in play. Because most API clients swallow the response body and surface only the status code, the single highest-value debugging habit here is to log the full response, headers included, before you touch any code.

If the quick fix above does not resolve it, work through these steps. They apply to this whole class of error, not just to this one message, which is usually what saves the time.

  1. Reproduce the failing call with curl -v outside your application. If curl succeeds and your client fails, the bug is in your client's header or serialisation layer, not on the server.
  2. Print the exact Authorization header being sent (redact the secret, keep the prefix). A missing Bearer  prefix and a trailing newline from an environment file are the two most common causes of a mystery 401.
  3. Check for an intermediate proxy. A 413 or 502 from nginx, Cloudflare or an API gateway looks identical to one from your application, but is fixed in completely different config.
  4. For webhooks, verify the signature against the raw request body. Any middleware that parses and re-serialises JSON before your handler runs will silently break HMAC verification.
  5. Confirm the API version. Deprecation errors and unexpected schema changes almost always trace back to a pinned version header that was never updated, or one that was never pinned at all.

Tools worth reaching for

  • curl -v
  • httpie
  • Postman/Bruno
  • mitmproxy
  • ngrok (for webhooks)

Authoritative references

Primary documentation for this error, worth reading before applying any fix in production.

docs.stripe.com docs.stripe.com

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This entry is maintained by hand. If the fix is out of date, incomplete, or you have a better one, email a correction and it will be reviewed.