I'd hope nobody would be rolling out upgrades on one of the busiest weekends of the year.
For what it's worth, and having seen and written about a few major IT omnishambles, I'd be surprised if this omelette wasn't made with swiss cheese. And that the motivation to find and fix the systemic error which allowed the holes to line up won't be sufficient to counter organisational inertia and CYA - but if it is, I'll regain that very scarce state of mind, respect for senior management.