What major problems did you face in your last role?The agenda of this question is to understand if -
- You caused the problem
- Could it have been avoided?
- Your attitude to solve it.
It is safer to mention a problem which was caused by an external party rather than the problems within internal parties. May be you can take an example of the problem caused by a customer, vendor. Discuss what you did to solve the problem. If you took some leadership role also in the whole process, talk about it.