stumbling block

Từ điển Oxford Advanced Learner 8th

ˈstumbling block [stumbling block stumbling blocks] BrE NAmE noun ~ (to sth) | ~ (to doing sth)
something that causes problems and prevents you from achieving your aim
Syn: ↑obstacle

Example Bank:
•Money could prove a stumbling block to the project.
•The negotiations have hit a stumbling block over the price.
•The question of disarmament proved a major stumbling block to agreement.
•The peace process encountered another stumbling block in mid-June.