Problems began around 11am on Tuesday and lasted for an hour, shutting visitors out of some of the world’s most popular web pages.
The New York Times, Guardian, Bloomberg and even HMRC websites were also struck down by outages.
Visitors to affected sites were met with a “503 error” message, and were unable to load the page. The message warned of a “connection failure”.
Websites have since been restored and are now working as normal.
Now its been revealed the huge outage was caused by a software bug which was triggered when a Fastly customer changed their settings.
The data center provider, which runs a service designed to speed up loading times for websites, has now apologized for the outage – and said it should have anticipated it.
Nick Rockwell, senior vice president of engineering and infrastructure, said: “We experienced a global outage due to an undiscovered software bug that surfaced on June 8 when it was triggered by a valid customer configuration change.
“We detected the disruption within one minute, then identified and isolated the cause, and disabled the configuration.”
Fastly will now carry out a “post mortem of the processes and practices we followed during this incident”.
‘WE’RE TRULY SORRY’
They added that they will do all they can to “figure out why we didn’t detect the bug during our software quality assurance and testing processes”.
Finally Mr Rockwell said: “This outage was broad and severe, and we’re truly sorry for the impact to our customers and everyone who relies on them.”
Its service requires it to sit between its clients and their users, meaning any wide-scale failure is likely to block visitors from web pages.
On its website, Fastly reported at 10:58am BST that it was investigating the issue, which it called a “global disruption”.
At 11:57am BST (6:57 ET), the company said that it had identified and fixed the problem.
Multiple websites have since been restored and are now working as normal.
A Fastly spokesperson yesterday told The Sun: “We identified a service configuration that triggered disruptions across our POPs globally and have disabled that configuration. Our global network is coming back online.”
The disruption hit hundreds of major websites, including Twitch, Pinterest, eBay, PayPal, Depop and the FT.
Visitors to the affected sites took to Twitter to vent their frustration.
One described how “everything just shut out of nowhere”, while another branded the outage an “internet apocalypse”.
Another tweeted that the internet was “broken”.