brick wall
noun [ C, usually singular ]
ukusa point or level that it is very difficult to go past:
The housing market declined as the boom in prices hit a brick wall.
a problem or situation that is very difficult to solve:
Their hopes to expand the company ran into a brick wall when they couldn't get a loan.
bang/hit your head against a brick wall
to try repeatedly to do something with no success:
It felt like I was hitting my head against a brick wall because I had no support from my boss.