OXFORD, Miss.—Thousands of country music fans were awaiting singer Morgan Wallen when he suddenly canceled his performance Sunday night at Vaught Hemingway Stadium.

WTVA-TV reported video boards inside the Ole Miss football stadium showed a message saying the “Thought You Should Know” singer had lost his voice and was unable to perform, adding that people would be refunded their money where they bought the tickets.

Some people expressed anger on social media because the announcement of the cancellation came after the opening acts had performed.

The sudden cancellation concluded what was supposed to be two consecutive nights of performances by one of the most popular stars in country music. Saturday night’s show appeared to be a huge success with thousands showing up for the first concert in the stadium’s history.