Media reports earlier said millions of users were affected, and thousands took to Twitter on Wednesday and Thursday to complain under the hashtag #facebookdown.
The lengthy disruption is likely to upset advertisers that spend large amounts of money to reach potential customers on Facebook platforms. Facebook product director Rob Leathern said on Twitter that people are also unable to access the social network's ad interfaces, which may exacerbate any lost revenue from the outage.
People went on Twitter to vent their frustration about the problems. The company also quickly dismissed concerns that the outage was the result of a distributed denial of service (DDoS) attack. Twitter even made the subject into a Twitter Moment.
As of Thursday, downdetector.com showed 37 percent of problems Thursday morning related to log-in; 32 percent with loading the newsfeed; and 30 percent a total blackout.
"Yesterday, a server configuration issue made it hard for people to access our apps and services. We've now resolved the issues and our systems are recovering", the company said in a tweet.
After staying tight-lipped on the cause of the outage for almost 24 hours, Facebook early Thursday afternoon blamed it on a "server configuration change that triggered a cascading series of issues". This is an important draw for people concerned with their privacy online, particularly in light of the fact that Facebook, Inc.is reportedly now under criminal investigation for secret data sharing deals.