A glitch in Facebook’s software allowed hundreds of thousands of individuals who had been blocked to message and view the profiles of those who blocked them, the company said.

The bug, which Facebook said popped up on May 29 and was fixed on June 5, affected 800,000 users. The social network has 2.2 billion monthly active users.

When a user blocks someone on Facebook, it severs the connection between their accounts, and prohibits the other person from seeing their posts.

Though the bug did not restore the blocked individuals as Facebook friends, it did make it possible for them to contact their blockers on Messenger.

In its blog post, Facebook said that 83 percent of the people impacted only had a single person blocked.

Facebook shares closed Tuesday’s abbreviated session down 2.4 percent, at $192.73.

Late Monday, it was reported that Facebook is facing an expanded federal probe over its ties to Cambridge Analytica and how much user data it shared with the now-shuttered consulting firm without permission.