Google has confirmed the worldwide service outage on Monday was caused by a technical fault inside its own systems.

The technology giant saw all its major apps, including YouTube and Gmail, go offline on Monday morning, leaving millions unable to access key services.

The company said the outage had occurred within its authentication system, which is used to log people into their accounts, due to an “internal storage quota issue” and apologised to users.

“Today, at 3:47AM PT Google experienced an authentication system outage for approximately 45 minutes due to an internal storage quota issue. Services requiring users to log in experienced high error rates during this period,” a Google spokesperson said in a statement.

Our dependency on technology has grown so much, but the amount spent on reliability, testing and quality hasn't grown in parallel

“The authentication system issue was resolved at 4:32AM PT. All services are now restored. We apologise to everyone affected, and we will conduct a thorough follow up review to ensure this problem cannot recur in the future.”

The incident had a far-reaching impact, as other Google services such as Google Maps, as well as Calendar and its cloud storage Google Drive app, were all listed as being affected by the outage on the company’s own status dashboard.

Visitors attempting to visit the YouTube website were met with an error message which said: “Something went wrong.”

Some of Google’s affected services are among the most widely used in the world – YouTube has more than two billion active users, while Gmail is the world’s most popular email platform with more than 1.5 billion users.

Service monitoring website Down Detector also reported that users had flagged issues accessing the Google Play Store and the Google Meet and Hangouts communications tools.

In the midst of the outage, many people took to social media to share their frustration with the rare service blackout, with the technology giant quickly trending on Twitter.

Responding to the incident, Adam Leon Smith, chairman of the Special Interest Group in Software Testing at BCS, the Chartered Institute for IT, highlighted the issues experienced by users of Google’s smart home products during the outage and said the incident showed how dependent on technology the world was today.

“People are sat in the dark unable to turn on their lights controlled by Google Home. My last two meetings have been unable to use the planned slides as they are stored in Google Slides,” he said.

“Our dependency on technology has grown so much, but the amount spent on reliability, testing and quality hasn’t grown in parallel. Many companies will be reviewing their SLAs (service level agreements) with Google today and realising their business is dependent on a stack completely outside of their control.”