(just) one of those days
A day in which many different things go wrong or not as desired; a frustrating or difficult day. Sorry for getting upset with you; it's been just one of those days. First the computer wouldn't turn on, then the Internet started acting up—I could tell it was going to be one of those days.
one of those days
Also, just one of those days. A day when everything goes wrong, as in The car wouldn't start, I lost my glasses-it was one of those days. This expression was first recorded in 1936.
one of those days
a day when several things go wrong.(just) one of those ˈdays
a day on which unpleasant things happen: It’s been one of those days. I lost my keys and then I fell over running for the bus. one of those days
A difficult or trying day.