"The time entered does not exist"

I normally schedule these blog posts in advance, and as I was scheduling one for today at 2:30 a.m., I got this helpful message from Blogger:

Because of a daylight savings time shift on the date entered, the time entered does not exist.

Of course it seems obvious now that I consider the matter: as we "spring forward" today we skip over an hour.  But it always happened while I was asleep, so I never thought that a date/time combination might just not ever happen.