Millions of Wordpress blogs were unavailable for almost two hours on Thursday after a datacentre problem caused routing issues and prevented blogs from being served to viewers.

The downtime was the worst experienced by Wordpress.org for four years and more than 10 million blogs were affected. The outage cost bloggers some 5.5 million page views and Wordpress-hosted blogs were unavailable for 110 minutes as a result.

The outage was blamed on the unscheduled changing of a core router at one of Wordpress’ datacentre providers and also took down safeguards meaning any blogs hosted by Wordpress were inaccessible during the downtime, although no data was lost.

“It also broke all the mechanisms for failover between our locations in San Antonio and Chicago. All of your data was safe and secure, we just couldn’t serve it,” said WordPress. “I know this sucked for you guys as much as it did for us. The entire team was on pins and needles trying to get your blogs back as soon as possible.”

The outage affected all regular blogs hosted by WordPress.com, as well as those sites hosted through the enterprise-class VIP service the company offers, including tech blogs like TechCrunch and GigaOM. Blogs which host Wordpress open source release on their own servers were not affected.