Tickets went on sale at 5 a.m. Tuesday for Ravinia's 2016 summer music lineup.
Ravinia typically sells more than 100,000 tickets, the equivalent of five United Centers, on its first day of sales, according to the festival's director of communications Nick Pullia.
By 6 a.m. Tuesday the festival's website was reported to be having issues processing the orders. Pullia told NBC 5 it was due to the credit card company the venue works with and they were working to resolve it quickly.
Customers are advised to stay online and to avoid trying to sign out before signing back in again, as that will only make the issue worse.
Tickets are available to the general public exclusively at Ravinia.org.
Among the more than 140 performers announced by the popular suburban venue to perform over the summer are Patti LaBelle, Bob Dylan, Diana Ross, Paul Simon, Steve Miller Band, Don Henley, Tony Bennett, Phillip Phillips and Matt Nathanson, Duran Duran, Buddy Guy and Jeff Beck, and the Barenaked Ladies.
Classical, jazz and family-oriented acts will also return to the Highland Park festival grounds, including the Chick Corea Trio, the returning Juilliard String Quartet, the Emerson String Quartet and the Chicago Symphony Orchestra.
Even Family Guy's Seth MacFarlane will be coming for a June 22 show.
The festival runs Thursday, June 2 through Sunday, September 11.
See the full calendar here.