Something small goes wrong, and this triggers something slightly bigger, which triggers something slightly bigger, and so on and so forth until you end up with a chain of problems of increasing severity until it ends in catastrophy.
Something like the old saying "for want of a nail the battle was lost", only highlighting that each intermediate issue was a problem in its own right, not just a stepping-stone to the final disaster.
Is there a common word/phrase that specifically describes this? I'm thinking "cascade of ever-increasing problems", but this seems clumsy, and I suspect there might already be a neat word or expression that covers it.