A friend left a Facebook group and now he wants to rejoin the group.
When I try to add him, Facebook tells me that "Mr.X has already left the group".
How do I add him back in again?
Facebook – Adding a friend back into a Facebook group who has previously left
facebook-groups
Best Answer
You'll have to ask the friend to request an invite back into the group. Once they leave, they burn the invitation from the first attempt and you can no longer add the same person.
This probably relates to people who were added to groups they didn't want to be a part of and left. This prevents them from being added again to groups they don't want to join unless they explicitly request it.