Mastodon and Dinosaur Jr. have canceled their upcoming tour due to a “critical situation of a member of the Mastodon family.” Dinosaur Jr. confirmed the news in a statement on Twitter, noting that tickets and VIP upgrades will be refunded. “We are sorry to disappoint our fans and Mastodon’s, and thank you for understanding,” they write. The tour was scheduled to kick off Saturday, September 1 in Edmonton, Alberta. Pitchfork has reached out to the bands’ representatives for more information. Find their canceled dates below.

Members of Mastodon have since elaborated on the reason for their cancellation. In an Instagram post, guitarist Brett Hinds revealed that the band’s long-time manager Nick John has been diagnosed with pancreatic cancer. “[He] has been fighting so hard that he is withering away and taking a little bit of me with him,” he wrote in the caption.

Drummer Brann Dailor has also shared a photo with John, writing, “I don’t know where Mastodon would be without him. He is absolutely integral to the success we have achieved as a band not to mention one of the best people you’d ever hope to meet. We all deeply love and care for him. Send your love his way.”

Following the cancellation, Dinosaur Jr. have announced a solo tour in September, which includes a string of intimate performances. See the full itinerary below.

This article was originally published on Thursday, August 30 at 3:13 p.m. Eastern. It was updated on September 4 at 2:38 p.m. Eastern.