Social media sites, including Facebook and Instagram, were briefly unavailable on Tuesday morning around the world, with a hacking group called the Lizard Squad claiming responsibility for the outage.
Both desktop and mobile sites were affected and the issue latest around an hour. Chat app AIM and dating app Tinder were also affected, according to reports.
There was speculation that the social media sites had been hit by a type of cyberattack called a distributed denial-of-service attack (DDoS), which is designed to slow down a website's user experience. A Twitter account which claimed to be associated with Lizard Squad posted a message saying it was behind the attacks.
However, Facebook denied that the outage was because of a cyberattack.
"Earlier today many people had trouble accessing Facebook and Instagram," a company statement, emailed to CNBC, said.
"This was not the result of a third party attack but instead occurred after we introduced a change that affected our configuration systems. We moved quickly to fix the problem, and both services are back to 100 percent for everyone."