Wimbledon organizers have apologized and explained that “human error” was the reason behind the electronic line-calling system being turned off during a match on Sunday.

Wimbledon has updated its electronic line-calling system after a human error caused the Hawk-Eye to fail during a fourth-round match. The All England Club has now issued a statement saying that they have made a crucial change that will ensure that the mistake doesn’t happen again.

Sonay Kartal was knocked out of Wimbledon after her Russian rival claimed the British player got special treatment when the electronic line calling failed on Centre Court. Anastasia Pavlyuchenkova, 34, recovered to knock the last British female out of the singles 7-6 6-4.