Facebook and its apps suffer another outage.

SAN FRANCISCO — Facebook and its family of apps were inaccessible for about two hours on Friday afternoon, the second time in a week that the social network experienced widespread problems with its services.

The site DownDetector.com, a service that relies on reports from users to determine whether websites are having problems, showed that all of Facebook’s main products — Instagram, WhatsApp, Messenger and the “big blue app” of Facebook — suffered downtime at around 3 p.m. Eastern time.

Just after 5 p.m. Eastern time, Facebook said it had fixed the issue, which had affected people around the world. The social network said the outage was caused by a “configuration” change, which typically refers to adjustments in the company’s underlying technical infrastructure, but it did not provide further detail.

“Sincere apologies to anyone who wasn’t able to access our products in the last couple of hours,” the company said

Facebook said that Friday’s outage was not related to problems it had on Monday, when its apps were down globally for more than five hours.

Monday’s outage was a stark reminder of just how much of the world relies on one or more of Facebook’s apps. More than 3.5 billion people worldwide use them regularly. Entrepreneurs and business owners said they were unable to make sales on Instagram or through their Facebook storefronts during the outage, in some cases costing them thousands of dollars.

Outside of the United States, people in countries that are heavily reliant on WhatsApp — Brazil, India and the Philippines, among others — were unable to communicate with friends, families, colleagues or customers. WhatsApp is used by more than one billion people globally.

After Monday’s outage, as the apps slowly came online again, the company cautioned that its services would take time to stabilize.