The error on Friday caused the social network to show a memorial banner on user profiles for people who were still alive.
Users posted status updates to reassure friends and family they were not dead, despite Facebook's message.
"This was a terrible error that we have now fixed," a Facebook spokesperson said. "We are very sorry that this happened."
The message, intended for "memorialised profiles", erroneously appeared on the profile pages of a large number of users - including Facebook CEO Mark Zuckerberg.
