What Is Error 503? Service Unavailable Message Greets Reddit, Amazon,Twitch Users

Error 503 was the ominous message many users received when attempting to access large parts of the internet on Tuesday morning. Many of the biggest sites in the world were ground to an unexpected halt, with users greeted by an error message.

The message read: "Error 503 Service Unavailable".

The outage affected news outlets such as The New York Times, CNN, Bloomberg, the Financial Times and British newspapers The Guardian, Independent and Evening Standard as well French newspaper Le Monde.

Live streaming services like Twitch and Hulu also appeared to be affected, as were HBO Max and PayPal. Social media platforms Reddit and Twitter also reported issues.

Similarly, internet users hoping to purchase something on Amazon on eBay were also left starting at the same message and the issue extended even to the British government's website.

Downdetector, an online service that collects reports of crashed websites, reported a sudden spike in crashed website reports across dozens of URLs.

Error 503 Service Unavailable indicates an issue which arises when the server cannot handle a particular request, either because it is down for maintenance or due to an expected overload.

Web apps that have been misconfigured may also lead to a 503 error, although that is a more remote possibility. Regular 503 errors could also be directly linked with an issue related to the domain name system, such as issue with the server itself or an incorrect server configuration.

In normal circumstances, the problem tends to be only temporary and refreshing the web page is normally enough to address it. Tuesday's outage, however, was caused by a problem at Fastly, an internet content delivery network used by many major websites.

Fastly runs what it calls an "edge cloud," which is essentially a service that speeds up website loading times.

Shortly after the outage was reported, the U.S. company said it was experiencing problems with its content delivery network (CDN)—a series of servers located across the world that provide fast delivery of internet content.

While CDNs do not host the website, they store website information and facilitates internet access by avoiding users having to fetch data from the original website, which may be located on the other side of the planet.

Fastly said the issue was caused by a problem with a Point of Presence—an access point or physical location at which two or more networks or devices share a connection.

The company encountered the issue just before 6 a.m. ET on Tuesday and by 6:44 a.m. ET it was working to address it. Less than 20 minutes later, the issue was resolved.

"We identified a service configuration that triggered disruptions across our POPs globally and have disabled that configuration," the company tweeted.

"Our global network is coming back online."

File photo: Some of the world's biggest websites were affected by an outage on Tuesday. Many users reported seeing the message "Error 503".