Facebook users trying to log in the social networking site were greeted by error messages as the site was hit by outages Thursday.
"The server is temporarily unable to service your request. Please try again later" is the message many users saw on the social network's login page.
People on various web sites reported issues with accessing Facebook. One site pointed out that the outage has taken the Like buttons with it.
"Facebook may be slow or unavailable for some people because of site issues. We're working to fix this quickly," Facebook announced over Twitter.
Facebook has more than 500 million users worldwide.
It is unclear what caused the outage.
We're currently experiencing some site issues causing Facebook to be slow or unavailable for some users," the company told CNBC. "We are working to resolve this issue as quickly as possible.