Limp Bizkit have postponed this summer's European tour due to an unspecified medical condition affecting frontman Fred Durst.
Durst told fans that he had had some tests to make sure he was in good physical condition ahead of the shows.
"To my surprise my doctor decided to send me a letter telling me he would not like me to tour at this time, and to stay close by to do more tests."
The band were due to play four dates in the UK in September.
Two were set to take place at Brixton Academy in London, with another gig planned in Birmingham and one in Manchester.
Durst said in a video message to fans that it was "very unexpected news and I'm so sorry and I look forward to making it up to you".
He added that he was "already working on something for the UK and all over Europe" in reference to hopefully rescheduling the shows.
Limp Bizkit said in a statement on Instagram that they "truly apologised for any inconvenience this may cause to our loyal fans, promoters and support staff".
The US rap rock band - made up of Durst, Sam Rivers, John Otto, DJ Lethal, and Wes Borland - were also due to play in countries including Germany, Austria and France.
Formed in 1994, their hit albums include Significant Other, Chocolate Starfish and the Hot Dog Flavored Water, while they also had success with singles such as Take a Look Around and the number one hit Rollin' (Air Raid Vehicle).