The bassist did not specify which band member is ailing in response to a fan question about their absence from the Back to the Beginning lineup.

On July 5, Ozzy performed his final concert — titled “Back to the Beginning” — with his band Black Sabbath. It was the first time the singer had reunited with the group in 20 years.

Ozzy Osbourne may have given his final performance, but he hasn’t yet given fans his final writings - or “Last Rites,” as he punningly puts it. His new memoir of that name will come out this fall, Hachette Book Group announced Thursday.