blind alley
nounUK /ˌblaɪnd ˈæli/
US /ˌblaɪnd ˈæli/
A blind alley is a street with no way out at the other end.
We walked down the blind alley and had to turn back.
OTHER MEANINGS
2. A situation or course of action that leads nowhere and brings no progress.
Arguing about it further is a blind alley.
3. A line of investigation or thinking that produces no useful result.
The detective realized the lead was a blind alley.
4. A plan or method that cannot succeed.
Trying to fix the old machine was a blind alley.