open Pandora's box

English

open Pandora's box (third-person singular simple present opens Pandora's box, present participle opening Pandora's box, simple past and past participle opened Pandora's box)

(idiomatic) To perform an action that causes problems to appear which did not exist beforehand, or were not known about prior.
- 2022 August 4, Adam Nayman, “Five Sci-Fi Classics, One Summer: How 1982 Shaped Our Present”, in The New York Times‎^[1]:
  It’s a thin line between charming, candy-flavored verisimilitude and craven commercialism, and if Spielberg ultimately stayed on the right side of it, “E.T.” nevertheless helped open a Pandora’s box of product placement.

to perform an action that causes problems