Facebook's blaming a "faulty configuration change" for its biggest ever outage.
WhatsApp, Instagram and Facebook were all down last night. The three apps stopped working just before 5pm.
The social media sites - which are all owned by Facebook - were out of action for nearly six hours. The outage affected 3.5 billion users.
Technology Correspondent, Jess Kelly, says there's little detail about what exactly happened;
"It seems that something within Facebook caused key digital records, that tell computers how to find the apps and websites were revoked."
She says it's not clear if it was intentional, human error or the work of a bad actor.
The "technical glitch" saw Facebook shares fall by almost 5 per cent. The problem wiped almost €41 billion off the group's share price.
Facebook Chief Technology Officer Mike Schroepfer tweeted an apology last night.
Facebook services coming back online now - may take some time to get to 100%. To every small and large business, family, and individual who depends on us, I'm sorry.
— Mike Schroepfer (@schrep) October 4, 2021
