Facepalm: Facebook has revealed that another bug was recently discovered in its systems. On this occasion, a glitch that was active between May 29 and June 5 resulted in blocked users temporarily becoming unblocked.

Facebook announced that over 800,000 people were affected by the issue during the one-week period it was active. It allowed those who had been previously blocked on the site to send messages to those who had blocked them.

Importantly, the bug never reinstated any friend connections that had been severed, but Facebook’s chief privacy officer Erin Egan explained that “while someone who was unblocked could not see content shared with friends, they could have seen things posted to a wider audience, for example pictures shared with friends of friends.”

Facebook added that 83 percent of people affected by the bug only had one person they previously blocked temporarily unblocked. Exactly how many users were contacted by individuals they had blocked is unclear.

The social network has apologized for the bug and is now informing those it affected via a popup message.

“There are many reasons why people block another person on Facebook. For example, their relationship may have changed or they may want to take a break from someone posting content they find annoying. Other reasons are more serious like harassment or bullying,” added Egan.

Less than one month ago, Facebook revealed it had discovered another bug—one that affected a lot more users than the unblocking glitch. It caused 14 million site members’ “suggested” sharing option to be set to “public” by default, rather than basing it on previous activity. Posting an update without noticing that the default setting had changed would mean messages intended only for friends and family could be seen by anyone.