Why is my checkout returning insufficient_funds?
insufficient_funds means the customer's card or account didn't have enough available balance to cover the charge — including any temporary holds. It's one of the most common payment declines in mobile commerce, and it's almost always invisible in product analytics because the reason lives in the payment API's response, not in anything your app explicitly logs.
You usually only find out from support tickets or a dip in revenue — long after the customer gave up.
How Drengr helps
Drengr reads the payment response in-process and annotates every insufficient_funds decline into a payment_attempt event automatically — no tracking code — so you see the count, the revenue at risk, and the trend in real time.