"The issue has since been resolved and we should be back at 100% for everyone," the company tweeted at 00:06 GMT Thursday, adding they were sorry for "any inconvenience."
A Facebook spokesperson, also speaking on behalf of Instagram and WhatsApp, explained that a "routine maintenance operation" accidentally triggered a bug that made it difficult for users to upload or send photos and videos, the US media reported.
According to DownDetector, thousands of users around the world were reporting outages, with Europe and North America most impacted. Both individual users as well as businesses and organizations were affected.
"Yes, we are affected by #instagramdown, too," the CIA tweeted during the outage.
"No, we didn't cause it. No, we can't fix yours. Did you try turning it off and back on again?"