We first noticed the problem a little after 0600 ET Tuesday when countless websites, including Reddit, Financial Times, PayPal, and other websites, went down. 

"We experienced a global outage due to an undiscovered software bug that surfaced on June 8 when it was triggered by a valid customer configuration change," Nick Rockwell, Fastly's senior vice president of engineering and infrastructure, wrote in a blog post late Tuesday. 

Rockwell said, "the outage was broad and severe, and we're truly sorry for the impact to our customers and everyone who relies on them." He said the company "detected the disruption within one minute, then identified and isolated the cause, and disabled the configuration," adding that "within 49 minutes, 95% of our network was operating as normal." 

"Even though there were specific conditions that triggered this outage, we should have anticipated it," Rockwell said.

The company operates servers at strategic points worldwide to support customers moving and storing content.

But when a customer switched their settings, they had accidentally exposed a bug in a software update issued in May, which triggered widespread outages.