"Yesterday, we made a server configuration change that triggered a cascade series of problems. As a result, many people had trouble accessing our apps and services," a Facebook spokesman said on Thursday.
A Facebook spokesperson told CNN Business that despite some online rumors, the problem was not caused by hacking or an attack, adding that the company was focused on solving the problem and hoping to eventually share details of what caused problem.
Interruptions, which also expanded to Facebook-owned services such as Instagram, Messenger and WhatsApp, are believed to be the largest ever by the social media giant.
In Washington, campaigns that have long called for Facebook breakup have said the outbreak showed how the concentration of technology platform ownership is "dangerous" to consumers.