Social media users have been struggling to access their favorite platforms due to site outages. A similar interruption last month that affected millions of people was blamed on a cyberattack.
For the second time in a month, Facebook was not loading for millions of users in the northeastern US, Europe and parts of Asia on Sunday.
Downdetector.com, a website that monitors site outages, showed the social media giant went down at 12:30 p.m. CEST (1030 UTC) in much of the world.
At one point, the site registered more than 14,000 outage reports from users, which is believed to represent just a fraction of those affected.
The website also showed that WhatsApp and Instagram — both owned by Facebook — also experienced severe outages around the same time.
Hours later, the services were restored, according to a Facebook spokesperson. "Earlier today, some people may have experienced the trouble connecting to the family of apps. The issue has since been resolved, we're sorry for any inconvenience," a spokesman told the Reuters news agency.
It was not immediately clear what caused the outage.
The hashtags #FacebookDown, #instagramdown and #whatsappdown were all trending on Twitter globally on Sunday.
Facebook has more than 1.52 billion daily active users, according to its website.
Last month, the social media giant experienced one of its longest ever outages, when millions of users around the globe faced trouble accessing the site, along with Instagram and WhatsApp for more than 24 hours.
Facebook blamed the previous outage on a hack.