Google says internal storage quota issue is to blame for outage on Monday

The authentication system outage lasted for about 45 minutes and took out Google services across the world

Google on Monday suffered a worldwide outage, disrupting the company's online services, including Gmail, YouTube, Google Docs and Google Maps.

The company has now revealed the reason for this outage, stating that it was caused by an internal storage quota issue.

"Today, at 3.47AM PT Google experienced an authentication system outage for approximately 45 minutes due to an internal storage quota issue," Google Cloud said on Twitter.

"Services requiring users to log in experienced high error rates during this period. The authentication system issue was resolved at 4:32AM PT. All services are now restored."

Google's authentication system is used to manage how users login to services run by both Google and third-party developers.

The company apologised to users affected by the outage and said that it will "conduct a thorough follow up review" to ensure that such issues don't recur in the future.

Millions of Google users took to social media on Monday, complaining that they were unable to access their Gmail account, YouTube and many other online services offered by Google.

Gmail users who tried to access their emails were greeted with a "Temporary Error" message, stating: "We're sorry, but your account is temporarily unavailable."

Soon after, #YouTubeDOWN, #Gmail and #googledown started trending on Twitter.

Google-connected devices, including Nest and Home speakers, were also affected by the issue.

In an update posted on the Google Workspace Status dashboard at the start of the outage, the company said that it was aware that many Gmail users were unable to access their account. YouTube also acknowledged the situation and said its team was looking into the issue.

After about an hour, the company claimed that the "problem with Gmail should be resolved for the vast majority of affected users".

The outage affected users around the world, according to the Down Detector site, although the largest number of reported issues appeared to come from the UK.

This is not the first time that Google has experienced a major outage disrupting its online services worldwide.

In August this year, Google users around the world reported problems with accessing Google services including Gmail, Drive and Docs. Thousands of users took to social media to complain that they were automatically logged out of their accounts, causing difficulties in sending and downloading email attachments and intermittent issues with Meet, Groups, Chat, Keep and Voice services.

In June 2019, Google blamed a 'network congestion' issue for the Google Cloud outage that took down YouTube, Snapchat, G-Mail and many other cloud services.

In a HackerNews post, a Google employee said that the outage was so severe that it even disrupted internal tools that engineers use internally to communicate with each other, thereby making the recovery process more difficult.

The Google outage on Monday follows a major failure at AWS in late November, which affected the US-East-1 region.

According to AWS, the outage was triggered by the addition of new servers to the Amazon Kinesis real-time data processing service. The issue resulted in a series of problems that eventually took down thousands of websites and services, including those from some big companies such as Adobe, Flickr, Roku, Twilio and Autodesk.