SAN FRANCISCO • Facebook blamed a "server configuration change" on Thursday for a massive outage affecting its applications around the world and brought fresh attention to the embattled social networking leader.
The outage affected users for some 12 hours in most areas of the world, including Singapore, with the biggest impact in North America and Europe, according to tracking website downdetector.com.
After acknowledging the problem on Wednesday, Facebook remained mum on the issue for nearly 24 hours before issuing an explanation and apology on Thursday.
"Yesterday, as a result of a ser-ver configuration change, many people had trouble accessing our apps and services," a Facebook tweet said. "We have now resolved the issues and our systems are recovering. We are very sorry for the inconvenience and appreciate everyone's patience."
The outage was believed to be the worst ever for the firm, which reaches an estimated 2.7 billion people with its Facebook, Instagram and messaging applications.
On Wednesday, Facebook said the situation did not appear to be the result of a denial-of-service attack. The hashtag #FacebookDown was a popular theme on Twitter.
In some cases, the apps could be accessed but would not load posts or handle messages.
Bloomberg News reported that Facebook was considering refunds for advertisers whose messages could not be delivered. Facebook did not immediately respond to requests for comment.
Meanwhile, The New York Times reported that US prosecutors had launched a criminal investigation into Facebook's practice of sharing users' data with companies without letting them know.
The news comes as regulators, investigators and elected officials worldwide examine the firm's data sharing practices.
The social network giant's handling of user data has been a flashpoint for controversy since it admitted last year that political consultancy Cambridge Analytica, which did work for US President Donald Trump's 2016 campaign, used an app that may have hijacked the data of 87 million users.
Facebook suggested there was nothing new in the report.
"It has already been reported that there are ongoing federal investigations, including by the Department of Justice," said a Facebook spokes-man. "As we have said before, we are cooperating with investigators and take those probes seriously. We have provided public testimony, answered questions and pledged that we will continue to do so."