Musician Julian Cope has pulled out of Belfast's Out to Lunch Festival due to "safety fears".
As one of the headline acts, he was due to perform in the Black Box in January.
But he emailed organisers, stating: "It is with regret that I feel obliged to cancel my forthcoming Belfast show of January 16th due to the current security situation there and the logistics involved.
"I'm very sorry about this."
The organisers have said they are stunned by the announcement and "hugely sorry" to have to cancel the gig.
Sean Kelly told the BBC the email was "sudden and inexplicable".
"In 15 years of organising festivals in Belfast, it's the first time we've lost an artist due to the security situation," he said.
"People have been critical of the artist, but I don't think we should rush to judgement too much.
"I take him at his word that he was genuinely fearful for his safety and we just have to deal with that."
Mr Kelly said the festival organisers hoped to be able to find another performer to fill the vacancy.
Anyone who bought tickets by credit/debit card will automatically be refunded, while those who paid in cash can get a refund from the Visit Belfast office.