Have you ever gotten the above email?
A few times over the years.
What did you do about it?
Respond honestly - and sometimes that hurts when you, your reports, or your team has to own the shortfall and the mistake.
How did you fix the issue?
Remediation, either by process or documentation to fix the broken things now and put things in place to prevent reoccurrence.
Were you scrambling to prove you didn't drop the ball?
Here's the deal - if I didn't drop the ball, I don't have to scramble. And if I did drop the ball - which happens to many people - there's no point in scrambling. If you work somewhere that will fire people for a dropped ball, then you're going to get fired eventually unless you're a scrambler.
Scrambling/covering/throwing others under the bus can save your bacon, but it roasts your soul. I'd rather admit to being a dolt than pretend to be smart.