Thieves Guild Glitch

For the Thieves Guild mission 'Trinity Restored' I am told to meet Karliah at the Shadow Stone. Once there, however, Karliah is nowhere to be found, and I cannot interact with the stone. The quest marker is on the stone, but I can do nothing.

Help!

proverbialshark

Put spoiler in the title because people will get angry. Anyhow, are you talking about the quest where you head to the stone after finding the vault empty?

I got the quest, fast travaled to sell items, went back, and then talked to Byrn. He mentiones that he trusts her and that you should hear her out. After that she come walking up and talks to you.

Is Byrn still standing around outside?

quote proverbialshark

Byrn is inside the Ragged Flagon Cistern where Mercer used to stand, and only says "I'm just as confused as you, lad"

I'm confused as to what point you're at. What is the last successful thief guild quest you have completed? If you are at meeting her at the stones Bryn should have told you that he has things to take care of first and that he will meet you at teh stones.

His two pieces of dialogue are "I think we can trust Karliah. Let's see what she's on about." And "I'm just as puzzled as you, lad."

Guess this will never be resolved :*(

So much for completing all the guilds :/

I'm not sure whether it's the marker or her position that is bugged but she actually isn't standing at the shadow stone - she is waiting about 30 meters north at a big black stone that's at the antrance to the cave (it is down below the rock, so you can't even see it from the shadow stone place).
Be aware of a couple of thugs - they might interrupt the conversation, so clear the area before going there.
Much bigger glitch occurs later in this particular quest. Fortunatley, the solution to walk around it has already been found and is available on skyrim wiki.

SEMI-FIX WILL ALLOW YOU TO GET THE ARMOUR BUT NOT COMPLETE THE REST OF THE THIEVES GUILD.

If you're on the PC stand infront of the statue where Karliah is supposed to be.
Then go to the console if you don't know how to use the console google skyrim console.
When the console is open type in "player.placeatme 1B07F" (no speech marks) and hit enter this will spawn Karliah at the nightingale statue and you can then proceed to talk to her.
When the door opens to the nightingale cave run through it until you find the armoury and then spawn her again in there. This will complete the next part of the quest and at this time you may then retrieve the armour.

Note: You're supposed to put the armour on and proceed down the hall to the gate and she is supposed to follow you but she wont and if you spawn her at the gate she will continuously try to open it with the chain but the gate will never open. (I have a theory but not tested if you look at the gate open the console and type "unlock" it might very well open the "unlock" conole command apparently unlocks anything so you could try that but past there I can be of no more help.
With this method you get the awesome nightingale armour but can't complete the rest of the thieves guild quests. Sorry that's the best I can do for you.