• Some visitors to websites in the U.K. and U.S. received error messages.
• Reddit and global news websites including the FT, New York Times and Bloomberg were all impacted.
• The intermittent outages came as U.S. cloud computing services provider Fastly experienced a technical issue.

Reddit and global news websites including the Financial Times, New York Times and Bloomberg experienced intermittent outages Tuesday morning, with some users unable to access the sites.

Some visitors to the websites in the U.K. and U.S. received the message "Error 503 Service Unavailable."

Amazon, Twitter, PayPal, Spotify, Twitch, the BBC and The Guardian were also affected, according to reports. Tech site The Verge used an open Google Doc to report on the story, although it forgot to turn editing off.

The first reports of the outage started around 6 a.m. ET, but sites were mostly back online for users an hour later. But some sites, including U.K. government website gov.uk and The New York Times experienced slow loading times and graphics issues.

U.S. cloud computing services provider Fastly said on its website at 5:58 a.m. ET that it was investigating a technical issue. At 6:44 a.m. ET, Fastly said the issue had been identified and "a fix is being implemented." At 8:41 a.m. ET, Fastly said the issue had been resolved. Fastly's stock was down 1.6% in premarket trading after the outage started. At one point, it was down about 3%.

Fastly operates a content delivery network. A CDN is a network of servers and data centers around the world that enable the transfer of assets needed for loading internet content like HTML pages, JavaScript files, images and videos.

Joshua Bixby, Fastly's chief executive, reportedly told the Wall Street Journal that the outage wasn't attack related. The company later wrote on Twitter that its POPs (points of presence) were disrupted by a file that has now been disabled.

We identified a service configuration that triggered disruptions across our POPs globally and have disabled that configuration. Our global network is coming back online. Continued status is available at https://t.co/RIQWX0LWwl

— Fastly (@fastly) June 8, 2021

The infrastructure that underpins much of the internet is operated by a relatively small number of companies. When one of them has a problem, it can lead to widespread global outages that affect billions of people.

"This is what happens when half of the internet relies on Goliaths like Amazon, Google and Fastly for all of its servers and web services," Gaz Jones, technical director of digital agency Think3, said in a statement. "The entire internet has become dangerously geared on just a few players."

When Amazon's cloud computing division, Amazon Web Services, encountered an issue in 2017, some of the world's biggest websites went offline for several hours across the entire U.S. East Coast. In 2019, Cloudflare, another CDN firm, experienced a problem that lasted around an hour and affected websites including chat service Discord and the dating site OKCupid.

Toby Stephenson, chief technology officer at IT and cyber security company Neuways, agreed that the incident "highlights the reliance of many of the world's biggest websites on content delivery networks."

"As there are so few of these CDN services, these outages can occur from time-to-time," he said. "By using these CDNs to push content to readers, these websites are usually fast and responsive, but on this occasion they have been left with egg on their collective faces. The technical backends of these big websites are probably fine, but it is the frontends that can't be accessed and content cannot be pushed as the network is down."