Facebook and its various platforms continued to face some outages on Thursday, with the issues stretching beyond 14 hours — believed to be the social network’s biggest-ever interruption.

Facebook says its lengthy outages over the past day were the result of a “server configuration change.”

The outages affected countless users and advertisers worldwide. Some people weren’t able to reach Facebook’s website and apps, including Facebook, Messenger, Instagram and WhatsApp.

Facebook did not say how many users were affected or why the outage was so long. In a tweet about 24 hours after the problems began, Facebook apologized and thanked people for their patience. It didn’t elaborate on the server change.

Meanwhile, the social media giant reportedly is under a criminal investigation for its data deals.

The Facebook family problems began Wednesday afternoon, forcing Facebook to use Twitter to provide an explanation.

At 12:41 a.m. ET Thursday, Instagram posted a tweet that said, “Anddddd… we’re back” with a gif of Oprah Winfrey. Users in Asia and Europe still appeared to be having issues with Facebook on Thursday morning.

Facebook did not say until later what was causing the outages. As of 4:45 EDT service was restored to some but other users were still reporting problems.

Via its Twitter account, Facebook said the outage was not due to a “distributed denial of service” or DDoS attack, a type of attack that hackers use to interrupt service to a site.

The lengthy disruption is likely to upset advertisers that spend large amounts of money to reach potential customers on Facebook platforms. The company’s flagship social network has more than 2.3 billion users, and Instagram has more than 1 billion.

Facebook stock fell more than 1% pre-market.

According to downdetector.com, which monitors websites, the outages started around 12 p.m. EDT on Wednesday in parts of the U.S., including the East and West Coast, parts of Europe and elsewhere. Both Facebook’s desktop site and app appeared to be affected. Some users saw a message that said Facebook was down for “required maintenance.”

Report: Facebook under criminal probe

The New York Times reports that federal prosecutors are conducting a criminal investigation into Facebook’s data deals with major electronics manufacturers.

The newspaper says a grand jury in New York has subpoenaed information from at least two companies known for making smartphones and other devices, citing two unnamed people familiar with the request. It reports that both companies had data partnerships with Facebook that gave them access to the personal information of hundreds of millions of users.

Facebook describes those data deals as innocuous efforts to help smartphone makers provide Facebook features to users before the social network had its own app.

The Times reports that it is not clear when the inquiry began or exactly what it is focusing on. Facebook did not respond to a request for comment.