Reference

Where it breaks.

Six common checkout failures, the symptom you will see in support tickets, and the design fix.

By Nagesh Koritala Reference Last verified: November 2026

All 16 pages in this guide

A checkout is a distributed system with money in it. Messages time out, people double-click, batches run late, and cards expire between order and shipment. Each failure below has a symptom you will recognize from support tickets, and a design fix.

Two holds, one order

Double submit

The shopper taps “Place order” twice, or the browser retries after a slow response. Two authorizations go out.

Fix: send an idempotency key with every authorization so the provider returns the first result instead of creating a second. Disable the button after the first tap.

Hold with no order

Timeout in the middle

The issuer approved, but the response never made it back. Your system shows a failure; the customer's bank shows a hold.

Fix: on timeout, query the status or send an authorization reversal. Never assume “no answer” means “declined.”

Capture declined

Expired authorization

A back-ordered item ships on day 12. The hold expired on day 7 (a common processor default; windows vary by brand and processor), and the capture fails.

Fix: track each authorization's expiry, reauthorize before capture when needed, and alert operations on aging orders.

Deposit does not match

Missing references

Finance cannot tie a deposit back to orders because the order never stored the capture's transaction ID.

Fix: persist every gateway ID (authorization, capture, refund) on the order, and pass your order number to the gateway as a reference.

Refunded twice

Refund after chargeback

Customer service refunds a customer who has already filed a dispute. The chargeback also succeeds. You paid back the money twice.

Fix: surface dispute status in the service tool and block refunds on disputed payments.

Tax mismatch

Quoted vs committed

Tax shown at checkout differs from tax on the invoice because the address, price, or rates changed in between.

Fix: quote at checkout, commit the final tax record at invoice or shipment, and use the same engine and inputs for both.

Notice the pattern. Almost every failure lives in a gap between two systems or a gap in time. Checkout, OMS, gateway, and ERP each hold their own copy of the truth. The work of a checkout team is to keep those copies in agreement, and to notice quickly when they drift.

Sources for this guide

Card network rules change. Time limits, fees, and authorization windows here reflect published rules and provider documentation as of late 2026; confirm details with your processor before you build against them.

Sources

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