Facebook, WhatsApp, and Instagram users around the world are breathing a sigh of relief as they are once again able to use their accounts again. Because, for around six hours on October 4th, all of Facebook's apps experienced a worldwide outage without warning.

Facebook has since provided an explanation and apology for this outage. Keep reading to find out why you couldn't use any of Facebook's apps for so long.

How Facebook Went Offline for Six Hours

On October 4, 2021, users around the world noticed they were having trouble accessing Facebook, WhatsApp, and Instagram. Some thought it was a wider internet outage, but it turned out to be an issue with Facebook itself, as all of its apps suddenly stopped working, causing a panic.

Users were unable to use Facebook, WhatsApp, and Instagram for around six hours as everyone wondered what was causing the problem.

The timing of the outage didn't help, coming the day after CBS News aired a 60 Minutes interview with Frances Haugen, AKA the Facebook whistleblower.

Haugen has made headlines by making some bold claims against Facebook. This includes claiming that Facebook profits from showing users hateful and divisive content, and claiming that Instagram is negatively affecting the health of teenage girls.

Read more: Who Is the Facebook Whistleblower and What Did They Say on 60 Minutes?

So, why were Facebook's apps down? And what caused this epic outage?

Why Facebook Went Down for Six Hours

Facebook's platforms are now back up and running, and Facebook has since apologized and offered an explanation for the outage. The social media platform has blamed the outage on a "faulty configuration change."

In a post on Facebook Engineering, the social network explained:

Our engineering teams have learned that configuration changes on the backbone routers that coordinate network traffic between our data centers 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.

In another post on Facebook Engineering, Santosh Janardhan, Facebook's VP of infrastructure, went into more detail about what happened and why. Janardhan confirms the source was "the system that manages our global backbone network capacity."

In a nutshell, during a routine maintenance job, "a command was issued with the intention to assess the availability of global backbone capacity, which unintentionally took down all the connections in our backbone network, effectively disconnecting Facebook data centers globally."

Facebook has vowed to learn a lesson from this outage, with Janardhan concluding:

Every failure like this is an opportunity to learn and get better, and there’s plenty for us to learn from this one. After every issue, small and large, we do an extensive review process to understand how we can make our systems more resilient. That process is already underway.

Is Your Facebook Data Safe After the Outage?

The first concern for many users is whether their data is still safe, considering how large of a corporation Facebook is. However, the company has sought to assure all users that they have no reason to be concerned, stating that there is "no evidence that user data was compromised as a result of this downtime."

We have no other option than to trust Facebook on this, but given the company's history and reputation, that's a big ask.