Hey guys, I found the key for the upper shaft on the dwarfs corpse, but when I try to open the door it still says "key required". I have tried loading up a previous save and still doesn't work. Has anyone else experienced this, or have any ideas?

There are 2 locked doors if I remember correctly. Explore around and you could probably find the other locked door.

The other doors are past the locked doors which I cannot pass

That's because when Geralt choose a path (Iorveth or Roche), he can't reach some areas, which are only available to the other path.

Geralt cannot be stuck in the game if he manages to find the appropriate key, or the unlocked way...

Only times I got stuck in front of such locked doors, I knew it was intentional ;)

Nope, subterranean life is on Iorveth's path, so all the doors should be open-able in the mine.

The warehouse door unlocks with a key that is in one of the last rooms you'll come across, so there's one door that you'll have to return to on your way out of the cave to unlock it.

Don't know if that's the door you're referring to though

You need to explore. All the keys in this quest can be found at the necessary level or above, but it takes a thorough search.