Tomorrowland, the biggest electronic/dance music festival in the world, has been forced to cancel its 2021 event by Belgian authorities.

Scheduled for Aug. 27-29 and Sept. 3-5, the festival has faced opposition, particularly in recent weeks, due to concerns about rising cases of the COVID-19 Delta variant. While just two weeks ago the Belgian national government approved outdoor events up to 75,000 people starting Aug. 13, the local governments of Boom and Rumst, the cities where the festival was scheduled to take place, have said they will not allow it to occur.

“We have just been informed that the mayors of Boom and Rumst will announce a ban on Tomorrowland 2021,” event organizers said in a statement. “That hits like a sledgehammer, very hard and unexpected.”

Tomorrowland organizers said they will appeal the local decision to the Belgian national government.

During a press conference Thursday in Belgium, government officials stated that while they love the festival, they must react to the current situation, fearing that at an event of Tomorrowland’s size and international appeal, they would not be able to properly ensure health and safety protocols.

Officials said that in order for the festival to happen, its roughly 75,000 daily attendees would need to get tested for COVID-19 each day of the event. The Belgian government stipulated that private companies cannot do the testing, and the police lack sufficient resources. The police have said that they would not be able to secure the festival grounds while also needing to check IDs and proof of vaccination.

Tomorrowland organizers responded, saying that their plans would mitigate the need for police to check IDs and vaccine cards. “No Tomorrowland for the second year in a row is in any case a gigantic disaster for our company, but also for the more than 1,500 suppliers involved, many freelancers and our thousands of employees. We are still 100% ready to organize everything as professionally as possible organizationally if the epidemiological situation allows and to celebrate a nice end of the summer with our visitors.”

They continued, “After 15 years of intensive cooperation, this feels very wry and we find it very unfortunate that after the many constructive preparations and conversations federal commitments have reached this point, where we no longer know what just happened to us and have to let it sink in for a while.”

While Tomorrowland had not yet announced a lineup, its 2019 performers included The Chainsmokers, Armin van Buuren, Carl Cox, Martin Garrix, DJ Snake and more. The Belgian festival would have been the first major dance event to happen since the start of the pandemic, with Electric Daisy Carnival Las Vegas postponing its May dates to October.