U2 frontman Bono abruptly called off a Berlin gig after just four songs after losing his voice.
The band apologised to fans, saying on its website: "We're so sorry for tonight's cancellation.
"Bono was in great form and great voice prior to the show and we were all looking forward to the second night in Berlin, but after a few songs, he suffered a complete loss of voice.
"We don't know what has happened and we're taking medical advice."
Bono had complained about the stage smoke, comparing it to that of a cigar and asked for it to be turned off.
He struggled as he sang Beautiful Day, and the situation got worse as he sang Red Flag Day. He stopped the performance and apologised, saying that another event would be arranged.