Chicago Pokemon Go festival goes awry when players can't log in

Eric Milovac of Minnesota was one of many who couldn't connect to the Internet at the Pokemon Go Fest Saturday in Chicago. (Erin Hooley/Chicago Tribune via AP)

A gathering of Pokemon Go aficionados in Chicago's Grant Park went wrong Saturday when a technical glitch prevented many players from logging into the game.

As many as 20,000 players had been expected at the event to mark the one-year anniversary of the augmented reality game's debut. Players use GPS to locate, capture, battle and train virtual creatures.

The Chicago Sun-Times reported that John Hanke, the CEO of game developer Niantic, was booed when he tried to explain the issue to the crowd. Hanke promised that "the whole Niantic team" was working to fix a glitch in the server and log-on problems with cellular service providers AT&T, Sprint and Verizon.

One man told the Sun-Times he was surprised that Niantic hadn't brought in equipment to improve cellular coverage in the park, adding, "I didn't expect it to go well."

Ryan Copple, who flew from Los Angeles to Chicago for Saturday's Pokemon Go Fest in Grant Park. (Erin Hooley/Chicago Tribune via AP)

At one point, the paper reported that Niantic's chief marketing officer instructed AT&T customers to migrate toward a specific cell tower near a corner of the park and suggested that everyone try using Wi-fi.

"Obviously, today has not gone as planned," Mike Quigley told reporters, according to the Chicago Tribune. "It has been a really unfortunate situation."

Early in the afternoon, Niantic announced that organizers would refund the event's original $20 ticket cost and receive $100 in credits for use on the Pokemon Go app.

Some in attendance paid as much as $400 online for the tickets when they sold out within minutes of their June release.

Niantic says Pokemon Go has been downloaded 750 million times.

The Associated Press contributed to this report.