Most people test a phone backup on the worst possible day: the morning the old phone will not turn on, the new one is in hand, and there is no time to fix anything. Android's built-in backup is genuinely capable. The problem is that it is not one system — it is several separate ones wearing a single label, and each of them can stop working without ever telling you. These are the five places a phone backup usually breaks, in the order you tend to discover them while restoring. 1. T...