Roblox has more than 43 million active daily users, 40 million games and 9.5 million developers, according to The Hill, which cites data from consulting firm Backlinko. The platform is especially popular among children from 9 to 12 years old, and The New York Times reported on mass unease as kids couldn’t play during the outage, which lasted October 28 to October 31.

Roblox CEO David Baszucki wrote on the company’s website that the outage “involved a combination of several factors.”

Baszucki said: “A core system in our infrastructure became overwhelmed, prompted by a subtle bug in our backend service communications while under heavy load. This was not due to any peak in external traffic or any particular experience. Rather the failure was caused by the growth in the number of servers in our data centers.”

He added that service took longer to restore because of difficulty diagnosing the initial problem.

As the BBC reports, Roblox has dismissed viral speculation that the outage was related to an in-game promotion from Chipotle. Nor was there an “external intrusion,” the company said to The Verge.

Major outages are fairly common, The Wall Street Journal notes, citing Facebook’s recent apology for downtime that affected its platforms and apps. According to a survey by Uptime Institute LLC, a consultancy, some sort of outage has hit 69% of data-center operators since 2018, with human error at issue in 78% of cases.

Still, gaming website Rock Paper Shotgun observes that compared with newer games, it’s rarer for an established platform like Roblox to go down, and for the outage to last such a long time.

GameSpot.com reports that Roblox had not yet fully explained what brought service down in the first place, with more details still expected as of press time.