There's a lot, A LOT of money in play here. Technical reasons are usually the cause, but I wouldn't completely discard sabotage if there's some way they could get away with it, if only to improve procedures.
reply(Assuming you are referring to last night's incident, not the 2016 one.)
replyNo, I wouldn't completely discard it. Nor would I limit sabotage scenarios to stealthy snipers. It could be anything from a suicidal pyromaniac with a hammer to a hacker messing with engine control software and prediction markets, to a nation-state actor.