For a brief window this morning, something strange happened to the internet.

At approximately 9:15am ET, display ads disappeared across mega-trafficked media websites such as BuzzFeed, Time, Forbes, Gawker and Vox, replaced instead by big, blank spaces. Some were understandably pleased at the mini-vacation they got from companies making money from their eyeballs, but those running the websites weren’t so happy—and neither was Google. It was the one who was supposed to supply those ads.

The end result? A ton of lost money for all those websites—and for Google. How much? That’s hard to say. But Google alone likely lost several hundred thousands dollars in about an hour and a half—and the other sites lost a comparable amount, if not more.

In the wake of the ads outage, Google scrambled to figure out what caused it, and by 10:45am, most websites were back to normal. Google posted a quick memo—which reads like a sigh of relief—saying things were back up and running.

The glitch was caused by the ad tool called DoubleClick for Publishers, or DFP—a Google advertising service used by many websites to manage ad operations, and whose content is hosted on Google machines rather than the servers that hold the publisher’s own content.

Read more on this story at Wired.