Users around the world are experiencing difficulty accessing social media sites Instagram and Facebook as well as encrypted messenger WhatsApp.
Those in the UK, US and Europe appear to be hardest hit in the latest in a string of outages.
Reports have come in from further afield, including Ghana, Australia, Brazil, Colombia, Japan, Mexico, The Philippines, Russia, Singapore, South Africa and Uruguay.
'We're aware that some people and businesses are currently having trouble uploading or sending images, videos and other files on our apps,' a Facebook spokesman said.
'We're working to get things back to normal as quickly as possible.'
Users around the world are experiencing difficulty accessing social media sites Instagram and Facebook as well as encrypted messenger WhatsApp. Pictured: Instagram outage map for Europe
Those in mainland Europe seem to be hardest hit as well as a smattering of people in the eastern United States. Pictured: Outage map for worldwide Instagram outage reports
Issues centre around posting to the news feed, seeing stories and loading content. Pictured: Outage reports for Instagram have grown from hundreds to thousands in the past hour
Facebook is not faring much better, with reports coming in from 1,200 users complaining that they can't access the social network - a figure that continues to grow
The picture is not much better for users of WhatsApp, the Facebook-owned encrypted messenger, with outage reports now numbering almost 1,000
Users began to report the issues in their hundreds to outage tracker Down Detector shortly before 2pm BST (9am ET / 6am PT).
They have continued to grow ever since, as more and more users across the US attempt to log on for the first time today.
Reports for Instagram alone via the site had reached 4,300 at the time of writing.
Instagram issues centre around posting to the news feed, seeing stories and loading content.
Facebook users say they are having trouble logging in and accessing their feeds, as well as viewing or posting pictures.
WhatsApp is failing to send or receive messages, as well as offering a poor connection and a small number of users are unable to log-in.
Bemused and confused users took to social media to bemoan the outage and ask if others were experiencing any difficulty getting online.
WHAT CAUSED FACEBOOK'S LARGEST EVER OUTAGE?
On March 14, 2019, Facebook experienced the largest outage in the social network's history.
There are a number of explanations as to why problems with Facebook's own hardware could have caused the outage.
The firm's claims of a 'database overload' on its network of servers could be caused by a range of internal complications.
The 500 'internal server error' messages detected by internet network analysts can be prompted to a variety of snags.
With a network of servers - the computers that relay traffic to and from the firm's apps and their users - as large as Facebook, complications are bound to arise.
Planned maintenance of the software databases used to ferry this internet traffic, as well as the hardware they are stored on, can lead to scheduled downtime.
In this case, the outage clearly caught the company by surprise, which would explain why it took them so long to bring their apps back online.
Facebook has so far remained tight-lipped over the exact cause of the 'database overload'.
Potential explanations include updates to the network's infrastructure that led to unintended consequences.
Another theory put forward suggests that an internet service provider (ISP) in Europe misdirected traffic from Facebook and this problem then spread across the internet.
A useful analogy to explain this explanation is a motorway's worth of cars being sent down a cul-de-sac due to an incorrect road signal.
The mass failure of components, which includes hard drive storage or power supplies, could also explain the outage, but this would seem unlikely.