Southampton FC has apologised after hundreds of fans were left queuing outside St Mary's Stadium and missed the start of the Premier League match against Manchester United.
Fans complained at missing up to 30 minutes of the first home game of the season at St Mary's.
The club said a new system to scan tickets took "significantly longer" than in pre-season testing.
It said all general admission ticket holders would receive a refund.
The Premier League tie on Sunday was the first competitive match played at the stadium since lockdown restrictions on crowd numbers were lifted.