Facebook, Instagram and WhatsApp crashed globally for six hours on Monday, October 4, 2021 due to a major power outage.
With services now back up and running, questions are being asked about what happened to Facebook, and why it took so long to fix.
What happened to Facebook?
Facebook, Instagram and WhatsApp went down for users shortly before 17:00.
The power outage also impacted Facebook Messenger and Facebook Workplace.
Why did Facebook go down?
On Tuesday Facebook issued a statement confirming that the cause of the outage was, "configuration changes on the backbone routers that coordinate network traffic between our data centers caused issues that interrupted this communication."
Why did Instagram and WhatsApp go down?
Instagram and WhatsApp are all owned by Facebook and are run on a shared infrastructure, so if there's one error it impacts everyone.
As all of Facebook's services were impacted by the power outage, they went down too.
This also included Facebook staff who have reported their employee passes no longer worked and that they were unable to access internal systems.
Why did it take so long to fix?
It took 5 hours to fix the issue.
This was because Facebook staff were locked out of their own systems, with some even unable to access their offices.
Facebook’s internal systems are run from a shared infrastructure so it took time for employers to realise what was causing the issue.
How many people were affected?
Downdetector, a website that monitors outages, said there were 10.6 million reports from around the world about the issue.
However, many people don't report and with more than 3.5 billion users, it's estimated to have impacted a large part of the world.
How much will this cost Facebook?
Facebook’s share price dropped nearly 5% on Tuesday with the business website Fortune, estimating it could cost Mark Zuckerberg an estimated $6bn (£4.4bn).
Could this happen again?
We've been here before!
In March 2019 a similar power outage left Facebook down globally for nearly 14 hours.