The Bundesliga match between Bochum and Borussia Moenchengladbach was abandoned on Friday after the assistant referee was struck on the head by a beer cup thrown from the stands.
Gladbach had been leading 2-0 at Bochum following second half goals from Alassane Plea and Breel Embolo when the match was interrupted after 71 minutes when linesman Christian Gittelmann took a blow to the head.
The referee took the decision to stop the game for good after 20 minutes.
Both clubs immediately took to social media to condemn the incident.
“We can only formally apologise to linesman Christian Gittelmann,” Bochum said on social media.