The bug would automatically unblock users that you may have blocked on Facebook, meaning they would be able to view some of your posts. When a Facebook user blocks another user, the latter (blocked user) cannot see things that the former posts on their profile, they cannot start a conversation with the former on Facebook Messenger and they cannot add the former user as a friend.
The company said Monday that the bug was active between May 29 and June 5. Users affected by the bug should expect to see a notification asking them to go over go over their blocked list.
An illustration picture shows a person posing during a photo session showing the social platform Facebook logo reflected in the pupil of an eye on April 25, 2018, in Paris.
About 83% of the 800,000 users affected had only one person unblocked. The social networking giant that doesn't consider itself a monopoly has said that a software "bug" unblocked some people who had been blocked by another user.
"We know that the ability to block someone is important - and we'd like to apologize and explain what happened", Egan said.
This year has not been good for Facebook as long as issues related to privacy are concerned.
The vast majority of the more than 800,000 people affected by the bug had only one person they had blocked be temporarily unblocked, according to Facebook.
It's worth noting that the issue didn't give previously blocked users full access to someone's account.
Facebook admitted that up to 87 million users may have had their data hijacked by British consultancy Cambridge Analytica, which worked for US President Donald Trump during his 2016 campaign.