Tickets went on sale for Microsoft’s yearly Build developer conference Tuesday, and the registration website was immediately flooded with takers–so much so, that users trying to sign up experienced technical problems throughout the morning.

Though many devs reported on Twitter that they had successfully registered, some posted complaints that they experienced long waits or needed to refresh the page repeatedly.

By midday, however, the problems seemed to be abating. So if you want to attend Microsoft’s biggest developer event, don’t delay: Build 2016 sold out the same day tickets were released.

Priced at $2,195, the conference will take place May 10-12 in Seattle. Along with technical trainings and hackathons, past conferences have included major announcements about new Microsoft projects and products.

A Microsoft blog post promises Build 2017 will cover the following topics:

  • Mixed-reality experiences

  • Cutting edge, intelligent cloud apps

  • Simplified end-to-end dev ops experiences

  • Mobile experiences for nearly any device

  • Apps that make your customers more productive

  • AI-powered apps we have yet to imagine