open a Pandora’s box
From Longman Dictionary of Contemporary Englishopen a Pandora’s boxopen a Pandora’s boxPROBLEMto do or start something that will cause a lot of other problems The report could open up a Pandora’s box of claims from similar cases. → Pandora's boxExamples from the Corpusopen a Pandora’s box• The internet has opened a Pandora's box of threats: its demons have been loosed on us all.• I've opened Pandora's box.