Payment gateway down. Revenue stopped.Fixed in 4 hours.

PM assigned in 10 minutes. Payment engineer starts diagnosing within the hour. Stripe integration breakages after dependency updates are almost always caused by: a breaking change in the Stripe SDK version that changed the method signature or removed deprecated features (check the Stripe changelog for your SDK version bump), a webhook signature validation failure because the webhook secret was not updated in your environment variables after Stripe rotated it, a breaking change in the Stripe API version Stripe pins your API version at account creation but library updates can override this, or a missing payment intent confirmation step that Stripe added to a newer authentication flow. The engineer traces the exact error from your Stripe webhook logs and application error tracker, implements the fix, and runs a full payment flow test before the session closes.

Yes. Robust webhook handling and payment recovery flows are standard Stripe integration deliverables. The engineer implements: idempotent webhook processing using Stripe's idempotency keys so duplicate webhook deliveries (Stripe retries failed webhooks for 72 hours) never double-process an order, a payment retry workflow for failed subscriptions using Stripe's Smart Retries or a custom retry schedule with exponential backoff and dunning email triggers, a failed payment recovery flow that sends a payment update link to the customer, proper handling of all relevant webhook events (payment_intent.succeeded, payment_intent.payment_failed, invoice.payment_failed, customer.subscription.deleted), and a webhook log table in your database for auditability. The engineer tests each webhook event type using the Stripe CLI before the session ends.

Multi-currency is typically a Full Day session or can be scoped into a half-day alongside other payment work. Stripe multi-currency involves: configuring Stripe Prices in multiple currencies rather than converting a single USD price at runtime (so exchange rate fluctuations do not cause pricing inconsistencies), implementing currency detection from the user's browser locale or billing address country, storing the customer's preferred currency in your database so their currency is consistent across sessions, presenting localised prices in the correct format (decimal separator, currency symbol placement, rounding rules vary by country), and testing that Stripe routes payments to the correct currency account or uses Stripe's automatic conversion. For PayPal, Razorpay, or Telr multi-currency, the engineer handles the provider-specific configuration in the same session.

API changes from payment providers are a common breakage cause Stripe, PayPal, Razorpay, Adyen, and Braintree all release breaking API versions periodically. The engineer handles the migration: reads the provider's migration guide and changelog to identify what changed, audits your existing integration code against the new API specification to find all breaking call sites, implements the updated API calls with the new method signatures or required parameters, updates your webhook signature validation to the new format if the provider changed their signing mechanism, runs a full integration test suite in the provider's sandbox environment, and deploys the update through your CI/CD pipeline. PM coordinates the deployment timing to minimise the window of payment downtime during the migration.

The five payment integration failures that cause the most unrecovered revenue loss: first, silent webhook processing failures your server receives the payment confirmation webhook but crashes before marking the order as paid, leaving the customer charged but the order unprocessed; second, missing idempotency keys causing duplicate order creation when the payment gateway retries a timed-out webhook delivery; third, 3DS authentication failures on European cards under PSD2 Strong Customer Authentication requirements cards that require bank authentication are silently declined if the SCA flow is not implemented; fourth, subscription dunning failures failed renewal payments that are never retried because the retry logic is misconfigured, causing unnecessary churn; fifth, currency rounding errors in cart totals that cause payment amounts to differ from what the customer saw, triggering fraud detection and payment declines.