Facebook and Instagram users have been unable to access services for the second time in a week.
The social media giants late on Friday apologised to users who are unable to refresh their home pages, though the outage appeared to be less widespread than on Monday.
About 2,000 people reported being unable to access Facebook at around 3pm Eastern Time (11pm UAE), said Downdetector, which monitors internet problems.
Facebook said on Twitter it was aware that some people were having trouble using its apps and products.
“We’re working to get things back to normal as quickly as possible and we apologise for any inconvenience,” said Facebook.
Instagram added: “We know some of you may be having some issues using Instagram right now.
“We’re so sorry and are working as quickly as possible to fix.”
Monday’s breakdown, which affected Facebook, Instagram and WhatsApp, left billions of the platforms’ users unable to get online for more than five hours.
Facebook, which owns all three platforms, said Monday's glitch was caused by a "faulty configuration charge".
It was one of the longest failures in recent memory.
The platform's second outage caps a calamitous week for the company that also included compelling testimony from whistle-blower Frances Haugen, who told the US Congress that Facebook prioritises its own profits before the well-being of its users.
This "dangerous online talk has led to actual violence that harms and even kills people", she said on Tuesday, noting that Facebook is "accountable to no one".
Ms Haugen also said in her testimony that Facebook primarily used artificial intelligence to search for hate speech, making it a popular device for alt-right extremists.
"We can have social media we enjoy that connects us without tearing our democracy apart our democracy, putting our children in danger, and sowing ethnic violence around the world," she said.
Agencies contributed to this report