The In Too Deep pop-punk legends are on their farewell tour, but their Aussie leg - including a co-headline slot at Good Things Festival - has been scrapped after advice from doctors.
As reported by Billboard, in a since-deleted statement the band wrote on Facebook: "It is with deep sadness and regret that we announce our 2024 Australian tour is unable to proceed.
"We were beyond excited to deliver this tour from December 4-December 12, and connect with our Aussie fans once more.
"Now that we're here though, and under the guidance and direction of multiple Australian doctors, it's clear that Deryck is too unwell to perform.
"We understand and appreciate your disappointment - we're gutted too."
It's said the Fat Lip hit makers still encouraged their fans to attend this weekend's festival.
"The good news is Good Things Festival is still going ahead in Melbourne, Sydney and Brisbane this weekend with an incredible line-up of local and international acts," they said.
"We can't be there, but get along for us and have the best time."
The festival - which will see Korn headlining with Jet, Billy Corgan, Violent Femmes and others on the bill - has sent "well wishes" to Whibley.
Sum 41 revealed earlier in 2023 they would be splitting after the release of their eighth album Heaven :x: Hell and a farewell world tour.