Niantic Labs apologized for the technical problems that players had at Pokémon Go Fest in Chicago on Saturday, and it will offer a full refund to those who attended.

As the company held a celebration event for the launch of its legendary Pokémon in the popular mobile game, a large number of players attending the event couldn’t play. It shows that staging live events for a lot of people in a single place isn’t that easy to do.

“Although we were able to solve many of the technical issues, we were not able to offer every attendee a great experience,” the company said.

Live events, such as the Chicago event, are one way that Niantic has used to generate excitement in the past (particularly for its Ingress game, the predecessor of Pokémon Go). The events get players to engage in the game again, and that helps improve both downloads and monetization.

Niantic said all registered attendees will soon receive an email with instructions on how to receive a full refund for the cost of their ticket. And registered attendees will receive $100 in PokéCoins in their Pokémon Go account.

The company also said that special Pokémon, eggs, and check-in PokéStops appearing during Pokémon Go Fest have had their range increased to a two-mile radius surrounding Grant Park through Monday morning, July 24.

These Pokémon and eggs will only be visible to Pokémon Go Fest attendees who validated the QR code they received when they entered Pokémon Go Fest. Attendees who were unable to validate their QR code during the event can do so through the special PokéStops through Monday morning. And all registered attendees will have the legendary Pokémon Lugia added to their account.

“We appreciate the patience of all the Trainers who joined us in Chicago this weekend,” Niantic said. “We will strive to make sure our experiences are of the highest quality going forward.”

The festival was supposed to highlight new features, such as an updated gym-battle system, as well as highly anticipated legendary Pokémon, which players will be able to catch through group raid battles. In its first year, Pokémon Go generated $1.2 billion in revenue and 752 million downloads.