In Greek mythology, what does the modern expression “open Pandora’s box” usually mean?

In Greek mythology, “open Pandora’s box” usually means to release unforeseen troubles.

The expression comes from the story in which opening a sealed container lets harmful forces escape into the human world. In modern English, it is used metaphorically when an action creates many new problems that are difficult to control or reverse.

The idiom does not require a literal box, nor does it normally refer to one specific kind of trouble. It can describe a political decision, a technological development, a legal dispute, or any intervention whose consequences expand unexpectedly.

The phrase is also a reminder that the popular version differs from the ancient account. Hesiod described a jar, not a box, and his treatment of hope is more ambiguous than many modern summaries suggest. Nevertheless, the idiom preserves the story’s central image: one opening unleashes a multitude of harmful consequences.