Criminal charges against 39 Legia Warsaw fans arrested after police were subjected to "horrific" violence outside Villa Park have been dropped.
Flares, bricks and bottles were thrown towards police outside the stadium in November ahead of an Aston Villa Europa Conference League match.
Five police officers and police dogs and horses were hurt in the clashes.
Charges against seven other Legia fans are being proceeded with, said the Crown Prosecution Service (CPS).
Forty-six Polish fans were arrested after the violence erupted when about 1,000 away supporters were not given tickets, West Midlands Police said.