This question is very similar to this one: Deleted myself from Facebook group and cannot regain access but specifically for a Facebook Messenger chat.
I was the sole admin of a Facebook Messenger chat, left the chat, and now no one can add me back because no one else is an admin. When someone tries it says new people need to be approved by admins, but there are no admins listed.
Can anyone promote themselves to be the new admin or is there another workaround?