Delaware News Journal Billie Eilish, The Killers, Tame Impala and Lizzo will headline Firefly’s 2021 lineup, it was announced Monday night. This year’s Dover festival, located in The Woodlands, will be held in the fall instead of summer for the first time, with event dates Sept. 23-26. Tickets go on sale Friday at 10 a.m. for fans who register for the presale at fireflyfestival.com. Major performers also include Megan Thee Stallion, Cage the Elephant, Roddy Ricch, Wiz Khalifa, Diplo, Glass Animals, Machine Gun Kelly and Portugal. The Man. State officials did not immediately respond to messages about whether the Division of Public Health has officially approved a plan for the four-day music festival. No details were released about possible COVID-19 restrictions.