Couple things can try, clear cache,data,force stop face book and messenger or go settings >apps>3 dots upperright corner tap scroll to reset app preferences and test again.
Facebook hasn't let me share links in messenger for over a week, I get no error on my phone but web browser on my desktop claims it is spam and won't send. I've got a friend experiencing the same issue.
L0n3N1nja thank you, but didn't work. donebrasko I am usually online, I long click the web address until "share" pops up. Then I chose messenger & it takes me there, but without the link.