He says it's the first time in 29 years he hasn't been able to finish a show.

Rob Zombie left the stage Sunday night Rock Fest in Cadott, Wisconsin after two songs, blaming throat issues.

He told Rock Fest promoters, "I knew from the first second we started that it was impossible to get through the show." Fans vented their frustrations online after they had to wait an hour before being told the show was over. The promoters said, "We tried to get him back on stage, but to no avail. That's what took so long."

Here's his apology which includes a photo of his throat.