The former Verve frontman appears to have strained his vocal cords after performing three gigs in two days before heading to the Woodford festival site on Sunday.
A doctor recommended he stay silent for 72 hours with Ashcroft's manager Jazz Summers also hooking the singer up with a throat specialist in Brisbane late yesterday afternoon.
"I am concerned about him continuing on to play Summersonic in Japan this weekend," Summers told music editor Kathy McCabe.
Ashcroft sang at the Million Dollar Lunch in Melbourne on Friday before performing for almost two hours later that night at his first Australian concert.
He played Sydney's Enmore Theatre on Saturday night for more than 120 minutes and conducted a slate of promotional interviews on both days.
After complaining of a sore throat on Saturday night, Summers canceled all his scheduled interviews at the Splendour gig on Sunday.
But when he got in front of the mic on the G.W. McLennan stage as one of the festival's closing acts, his voice was almost gone.
Midway through the first song Are You Ready, Ashcroft threw his mic stand and stormed off stage, frustrated he couldn't sing.
Summers denied that Ashcroft was angry at the size of the crowd in the tent or that the majority of fans had gone to see The Pixies.
The setlist for the show (above) reveals that he was planning to close the festival with the Verve classic Bittersweet Symphony.
- Source: news.au.com