Facebook faced its worst outage in over four years Thursday, according to an engineer for the site. Robert Johnson said millions of the half a billion users of the site were unable to access it at all for around 2 and a half hours. The outage started about 2:30 pm ET.

The cause of the problem was an error in the system that is designed to fix errors. This overloaded the database to the point where nothing on the site was working properly. That caused the engineers to have to shut down traffic to the database completely. The only way to do that was to shut off the site temporarily. Once the problem was fixed, people were slowly allowed back onto the site.

Johnson stressed that the company takes the site’s performance seriously and apologized to the users on behalf of the company.

Many who used Facebook Connect found that the outage also affected their internet surfing.  Thousands of users flocked to Twitter to discuss the outage.

The site was back up and running in less than three hours. Many found humor in the situation, saying that perhaps the recession would end due to the increased work  productivity while Facebook was down.