The internet users across the globe were in for a rude shock when WhatsApp, Facebook and Instagram went kaput on Monday evening. Several uses thronged to Twitter to reconfirm whether the issue was with their network or did the Facebook-owned apps really go down. It took over six hours for Facebook to resolve the issue that the company claimed arose due to a “faulty configuration change”. WhatsApp’s outage affected over 3.5 billion users across the globe.

The interesting bit about the Facebook outage was just how severe it was and how it not only made services like WhatsApp inaccessible but also made facebook.com and its servers disappear from the internet. It was as if the whole of Facebook simply vanished.

This was one of the longest outages Facebook and its services like WhatsApp faced. Soon after the reports of Facebook going down spread on the Internet like wildfire, the conspiracy theorists claimed that the outage has happened due to a massive hack. However, the chances of any possible hacks were ruled out by Facebook in its blog hours later. The blog noted that the cause of the global outage was a glitch in routers. Facebook has blamed the faulty configuration change behind the outage.

Here is everything that went wrong with WhatsApp, Facebook and Instagram

— At around 8:45 pm on Monday, outage tracker Down Detector reported that WhatsApp, Facebook and Instagram were down. Users were unable to load the feed on both Facebook and Instagram. The users were met with “connection error” messages every time they tried to refresh their Facebook and Instagram feed. Similarly, on WhatsApp, users were unable to send or receive messages.

— Facebook acknowledged the issue as soon as it was reported and assured that the services would be back. However, it didn’t happen as promised. Facebook, WhatsApp and Instagram were persistently down even hours after it was reported. Facebook’s outage was Signal’s gain as it saw an influx of users, who turned to the WhatsApp rival when they were unable to communicate using the messaging app.

— With services down for hours, web users started realising that this time it was something severe that hit Facebook. Many people speculated that Facebook has been knocked offline by cyberattack, or maybe a disgruntled Facebook employee has messed up the company servers. However, people more familiar with how the internet works correctly identified that the problem was with Facebook’s DNS servers and BGP (the local peering network that Facebook uses).

The interesting part about the glitch was how it made Facebook servers, including the servers for Facebook.com, vanish from the internet. These servers refused to even receive a ping via TRACERT. The extent of the outage was so severe that even Facebook executives could not assess the glitch because the security systems acted as a hindrance. All the electronic doors and locks reportedly stopped responding. As a result of which, Facebook employees had to force their way into their server room in Santa Clara. The security badges of the engineers had become non-functional due to the outage because of which they had to barge in like intruders, the New York Times report. Interestingly, the Facebook employees were forced to use other messaging apps like Discord to communicate with their fellow team members.

— Almost six hours after Facebook managed to restore the services, the social media giant listed the reasons behind the massive outage. Facebook said, “ Our engineering teams have learned that configuration changes on the backbone routers that coordinate network traffic between our data centres caused issues that interrupted this communication. This disruption to network traffic had a cascading effect on the way our data centers communicate, bringing our services to a halt.” The social media company also noted that it has no evidence that user data was compromised as a result of this downtime.

— It is being reported that Facebook CEO Mark Zuckerberg lost more than 7 billion dollars because of the outage that lasted around for more than 6 hours.