(USA Today) -- Access to Facebook's website and apps went down just before 4 a.m. ET on Thursday, shutting out millions of users for a brief period.
The outage affected the homepage as well as mobile and Messenger services around the globe.
Facebook says it is now "back to 100 percent.
For about half an hour, users who tried to access Facebook in the United States, United Kingdom, Ireland, Israel and India received the following message: "Sorry, something went wrong. We're working on getting this fixed as soon as we can."
Problems were also reported across multiple nations in Asia and the Middle East. Shortly after the outage, #Facebookdown started trending all over the world on Twitter.
"Late last night, we ran into an issue while updating the configuration of one of our software systems," a Facebook spokesman said. "Not long after we made the change, some people started to have trouble accessing Facebook. We quickly spotted and fixed the problem, and in less than 30 minutes."
Facebook said it learned from the experience.
"This doesn't happen often, but when it does we make sure we learn from the experience so we can make Facebook that much more reliable," the company spokesman said. "Nothing is more important to us than making sure Facebook is there when people need it, and we apologize to anyone who may have had trouble connecting last night."
Scott Kessler, head of technology sector equity research at S&P Capital IQ, said the response to the outage speaks to Facebook's new status as a "critical social utility."
"This just reminds us how central and critical Facebook is now to many people's lives, not just on a day-to-day basis but on an hour-to-hour basis," Kessler said.
Kessler said the outage may also make a slight dent in advertising revenue and could even concern some marketers.
"It just reminds folks who are looking at Facebook as an outlet to deploy advertising that as much as this might be a 99.99% uptime kind of platform, it's perhaps appropriate at times to account for the possibility of down time," he said.
For Facebook to suffer such a widespread and lengthy outage was unusual. The Menlo Park, Calif., company did not provide details on the cause. But it was not a welcome development for the world's most popular social network which is trying to boost advertising revenue overseas. Eighty percent of its nearly 1.3 billion users are outside North America. In April, Facebook reported that first-quarter revenue rose 72% higher to $2.5 billion.
Facebook does not frequently have outages, but has had several over the last few years. In 2010, the company took the unusual step of explaining an outage in a blog post from its engineering team. The blog post said the outage was caused by an "unfortunate handling of an error condition."