That's leaving the folk festivals in Edmonton and Regina in the lurch, given that the events are only a couple of weeks away.
On its website, the Edmonton Folk Festival says it is "disappointed" at O'Connor's cancellation and says it will try to replace her, "but given the short timeline this might prove to be difficult."
The festival says it will offer refunds to patrons holding tickets for the Aug. 7 performance where O'Connor had been slated to perform.
The Regina Folk Festival is in the same boat, saying it will try to replace her but refunds will be available for Aug. 9 ticketholders.
A statement from O'Connor's agent says she "has been advised by the doctor to stop any activity and rest."
The 48-year-old O'Connor was in the news last week for her criticism of Rolling Stone magazine for putting celebrity socialite Kim Kardashian on the cover.
“Music has officially died," O'Connor wrote on social media. "Who knew it would be Rolling Stone that murdered it?”
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