CMC Rocks has sold out in record time this morning.
Country music fans snapped up 18,000 tickets, up from the event's 15,000 capacity last year, in less than an hour.
Last week American country music superstar Luke Bryan was unveiled as the 2018 festival headliner. It will be his first-ever tour of Australia.
"CMC Rocks fans are the best audience and are super passionate about this festival," said festival director Rob Potts.
"Today, they get to celebrate Australian country music history with us. The biggest and fastest sold out country music event ever in Australia. Thank you CMC Rocks fans!"
Kelsea Ballerini, Darius Rucker, Busby Marou and Dustin Lynch are also on the bill.
"To say we were taken by surprise this morning is an understatement," Michael Chugg, executive Chairman of Chugg Entertainment, said.
"To sell out in less than an hour is an amazing testament to the growth of the country music genre in Australia. We are all very proud, and are looking forward to our eleventh year, and the most amazing line-up yet."
But not everyone is happy. Dozens of fans have taken to the festival's Facebook page to complain about issues with buying tickets.
Jesse Stirland wrote: "was on right on ticket release, green room for 25 minutes put tickets into my cart entered card details then sold out wtf?"
Ellen Freeman had similar issues: "I tried for over an hour and each time I selected tickets they were still available only to be told they were exhausted at payment even though I could start a new order selecting the same tickets that were still available."
In a statement addressing the issues, festival organisers said: "Demand for CMC Rocks has grown dramatically over the past three years. Unfortunately, when demand exceeds supply, there are going to be disappointed fans as we have seen this morning. We increased capacity by 3000, up to 18,000 for the 2018 event, but even these additional tickets were snapped up almost immediately."
Organisers have advised anyone who has missed out on tickets to join the official waitlist and confirmed some tickets are likely to become available closer to the event either because of ticket holders who can no longer attend or those who opt for Time To Pay but don't complete the process.
CMC Rocks plays Willowbank from Thursday March 15 (first day campers only) to Sunday March 18.
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