The social network is notifying more than 800,000 users "about a bug in Facebook and Messenger that unblocked some people they had blocked" between May 29 and June 5, Erin Egan, Chief Privacy Officer, wrote in a blog post. Facebook, instead, allows these users to connect via Messenger, while a previously blocked person may also be able to spot public posts from the person.
It should be noted that in the week or so this bug remained active, a large majority of users had only a single person from their blocked list temporarily unblocked. "We know that the ability to block someone is important - and we'd like to apologize and explain what happened".
The unblocked users were not able to see content shared with the friends of those they'd been blocked by, and the bug "did not reinstate any friend connections that had been severed". Blocking also automatically unfriends them if you were previously friends.
For the second time in less than a month, Facebook is having to alert users that their accounts may have been negatively impacted because of a bug. Unblocked users have been blocked again.
Do you block anyone on Facebook? For example, their relationship may have changed or they may want to take a break from someone posting content they find annoying.
About 83% of the 800,000 users affected had only one person unblocked. "Other reasons are more serious like harassment or bullying", she said.
Apparently, the bug did not cause unblocked users to become friend with the users who had blocked them even if they were friends before getting blocked. They would also have been able to send messages to the user, something a blocked person usually cannot do.