Photo-sharing app Instagram announced it was back up and running, but users are still having difficulty accessing Facebook, according to Down Detector.
Euronews has reached out to Facebook for comment but did not receive a reply at the time of publication.
The outage, looking at Downdetector.com - is worldwide but hitting the US and Europe fairly hard.
Facebook did not say what was causing the outages.
Some users took to Twitter to air their grievances.
Third-party outage tracker Down Detector said the worst hotspots were in California and NY in the USA, and in the UK.
Malaysia won't drop case against Vietnamese in Kim killing
He also sought a deferment of the trial, saying Huong has been unwell since Aisyah's release and is not in a position to testify. Vietnam's foreign ministry said it regretted the Malaysian court's decision not to immediately free Huong.
The issues affected users around the globe, with people in the US, Europe, Asia, Australia, and South America reporting problems. All they could see was older posts and not the latest ones that should have appeared on the site.
While users could open the apps, they could not access many of their functions, and there were reports of people being unable to sign in to Tinder or Spotify through Facebook either.
Some media outlets branded the outage as the biggest in Facebook's history.
Facebook has acknowledged the outage and has stated it is working to resolve the problem "as soon as possible".
A message on Facebook's login screen reads: "Facebook is down for required maintenance right now, but you should be able to get back on within a few minutes". Some users have regular access, and some have intermittent access.
- Jung Joon-young: K-pop star quits over secret sex videos
- Eye exam detects signs of Alzheimer's disease
- Prime Minister May Strikes New Brexit Deal - But Will Parliament Approve?
- Beto O’Rourke tells Texas TV station he’s running for president
- Lori Loughlin allowed to continue filming in Vancouver after bribery indictment
- Microsoft’s ‘Phantom White’ Xbox controller is gorgeous and available to preorder
- US consumer prices rose 0.2 percent in February
- Tucker Carlson's Refusal to Apologize Is the 'Fox News Brand'
- Captain Marvel Joins The Fight Against Thanos In 'Avengers: Endgame' Trailer
- U.S. Equities Gain With Europe as Pound Advances: Markets Wrap