Rage Against the Machine have cancelled their European tour, including headline slots at the Reading and Leeds festivals, because of a medical issue involving singer Zack de la Rocha.
The news comes two weeks before the US band were due to headline the twin UK festivals and play a date in Edinburgh.
A statement said the frontman was following "medical guidance".
It didnt specify the medical issue, but de la Rocha, 52, injured his leg on stage in Chicago in July.
The rock group, known for the 1993 anti-authority anthem Killing in the Name, resumed their US tour with de la Rocha performing seated, and will play three more shows in New York this week.
"Then Zack must return home for rest and rehabilitation," Thursdays statement said. "The flights, travel time, and rigorous schedule in the UK and Europe are simply too much of a risk for a complete recovery.
"We are so sorry to all of our fans who have waited years to see us and hope to Rage again soon."
The band had originally been booked to headline Reading and Leeds in 2020, but that was called off because of Covid.
Festival organisers have not yet announced a replacement. The Arctic Monkeys and Dave are headlining the other days at the event, which takes place from 26-28 August.
Rage Against the Machine have also cancelled dates in France, Belgium, Germany, Switzerland, Spain, Austria, Poland, Croatia and the Czech Republic.