090 Can of worms

Can of worms

(PW)complex problem or complicated situation

It opened up a large can of worms when the company decided to talk about the union contract.

(Wiki)A can of worms is a complex, troublesome situation arising when a decision or action produces considerable subsequent problems

(Answers)

n. Informal, pl., cans of worms.
A source of unforeseen and troublesome complexity.