Me yesterday: "Oh this story looks interesting, but I really can't read it right now. I'll open the tab and read it tomorrow!"
Cohost today: "This user doesn't exist any longer."
Me: "... ah."
Edit: I guess it was a new user that changed their name? There should really be... some kind of redirect or something. Sort of like how twitter gave 0 fucks about what user you put in the url, as long as the Actual Number That Means Something was correct.