Another bug. This game is so beautiful as so broken.... Anyway I've a serious problem with the quest Waking Nightmare. For first, I had a problem in the Nightcaller temple entrance, because when I enter in it, Erandur don't followed me. But I've resolved this with a re-load of previous save.
Now I've another problem. After the first fight with orcs and the scene with Eradur that speak about the blue barrier and of his past, then he stuck. I need it to open the library door. How can I do? Re-load previous saves don't work.

try using unrelenting force on him, sometimes that can get a stuck npc moving again.

Yes. Seems that FUS-RO-DAH and push him into the door, work.