Facebook is undergoing one of its most widespread and persistent system outages, with users across the globe unable to access its social network and services from Instagram to Messenger for much of Wednesday, and into Thursday.

From about noon New York time Wednesday, users encountered only partially loaded pages or no content at all, accompanied by a message saying an error had occurred. Several brand marketers tweeted that Facebook’s ad-buying system was down as well. The company said it was still investigating the overall impact, “including the possibility of refunds for advertisers.”

Ad sales are the company’s lifeblood and persistent difficulties could be costly. Based on 2019 sales estimates, Facebook Inc. is projected to generate average daily revenue of about $189 million.

Facebook shares (FB) were down 2.3 percent during pre-market trading at 6:51 a.m. in New York Thursday.

Reports on Downdetector, a website for reporting problems on applications and websites, have ranged from troubles logging into accounts to an inability to post comments or photos. Regions affected include the New York area, parts of California and the Seattle region, according to Downdetector. Other problem locations include Japan, the Philippines, Peru and major cities in Australia.

Users cited snags not only with Facebook, but also photo-sharing site Instagram, messaging tools Messenger and Whatsapp and Oculus virtual reality devices. Instagram however resumed service shortly after midnight, the app tweeted from its official Twitter account.

Some users encountered a message indicating Facebook was down for maintenance. “We’re aware that some people are currently having trouble accessing the Facebook family of apps. We’re working to resolve the issue as soon as possible,” a Facebook spokesperson said.

The timing of a major outage is sub-optimal for Facebook, already embattled by revelations it failed to safeguard user data or stanch the spread of hate speech, fake news and other forms of disinformation. Facebook’s reputation was tarnished after its platform was used by Russian trolls to interfere in the U.S. presidential election in 2016.

A U.S. Justice Department investigation into the company’s data-sharing practices broadened to include a grand jury, a person with knowledge of the matter said Wednesday.

The stock had climbed less than a percent to $173.37 as of the close of U.S. trading, and it has lost more than 20 percent since reaching a peak on July 25.