The Prince of Darkness, Ozzy Osbourne, had to pull out of his concert in Mannheim, Germany last night (June 20) due to what is being explained as “vocal concerns”.

TMZ reports that after Zakk Wylde‘s group, Black Label Society, had performed their opening set, an Osbourne representative took to the stage to announce that Ozzy would not be able to perform for the fans gathered in the SAP Arena.

Osbourne is currently on tour through Europe on the Ozzy Osbourne & Friends tour, performing shows that had been scheduled for the legendary Black Sabbath before guitarist Tony Iommi’s battle with lymphoma had begun.

Tour support for the run of European shows is being handled by Black Label Society while special guests including Ozzy’s Sabbath band mate Geezer Butler and Slash are slated to join various stops on the tour.

There has been no lack of news-worthy items relating to Osbourne over the past week. Earlier this week, Osbourne’s son Jack came forward to disclose that he has been diagnosed with multiple sclerosis. Yesterday however, Osbourne called his son’s diagnosis into question, stating that he himself was falsely diagnosed with the condition in the past.