In reference to the other thread...you might not need to do that, but by travelling there it might fix the quest bug when you come back.

nope tried going there, i was reading other posts abount this glitch but none of what they said worked, and yes i tried going back and forth to find him or maybe the lady (now i know she dissapears) but none of it works

Ok, looked around for a bit, this seems to be a fairly known problem, that will occur if you mess up the quest order... There are a couple of threads discussing this in CDPRed's own witcher forum, and, well, this very subforum has at least one thread about this. Might be some helpful advice there?
I guess you could also try messing around a bit with the save editor
which seems to be how people on the CDPR forum fixed the problem.

can you help me with using save editor? its working and all but i dont know what to do with the quests exactly, i can do stuff with them but i dont know what exactly should i do.

I can try, but I really can't promise anything. Do you have a save or two you could upload somewhere?

have i dont know where can i upload them or how :P

You can just use www.zippyshare.com (or similar) - you upload the file, and the website will create a shareable link for you ;)

http://www65.zippyshare.com/v/0dUFEbNv/file.html if nothing else works try with this one

http://www65.zippyshare.com/v/MIZ3Y45l/file.html if first doesn't work try this

http://www65.zippyshare.com/v/TkwEeAeV/file.html try this first

if you cant do anything with them i can give you even older saves.

;)
I'll try my very best...

thx a lot even for trying, i hope you can do it

Dear Knurek,
So, I done and fixed it. Sweet mother of mercy, that was quite a pain. You can thank your lucky stars that I'm stubborn like a mule (and also really want people to play The Witcher) ;)
Firstly, your save:
http://www34.zippyshare.com/v/Sh1e6wwy/file.html

It is practically the same file you sent me (the one you wanted me to use). You're at the same place, about to talk to the Lady of the Lake, and can now either
- not talk to her, and go back to the Mainland to finish some quests (I played around a bit, and there's a bit of stuff you haven't done/seen (minor sidequests, some dice poker etc), so you can do that if you want.
- talk to her, at which point Path of Destiny will advance, Berengar will come talk to you etc, and events move forward quickly and you can move on to chapter 5 if you want.

The save does definitely work, if you get some error the problem should be on the upload/download side of things, just let me know and I'll upload again.
Since I know how to do it now, if you do have a "newer save" (after more grinding/sidequests solved or whatever) don't hesitate to send me one, it should be fixable no matter how late in Ch IV you are - again, can't promise it works, but I think it should work with a newer save also.
I'll make a longer post explaining the problem and how to do fix it, should anyone run into the same problem (just got to do some stuff AFK for a bit).

Happy playing :)

The problem and how to fix it (if anybody happens to run into the same issue)

So, I fiddled around with this a lot, and it seems at least in this particular case, the problem is not anything you do or don't do in Path of Destiny or Ripples, it's actually the Alvin quest that is screwed up. There's a possibility that there are other ways you can get stuck in chapter IV, but I'd venture a guess that this is what usually happens.

There's a non-optional (!) conversation you need to have with Alvin that serves as a trigger for progressing in other quests. If you progress Ripples/PoD/Alvin before you've had this conversation, the game will not tell you that this is what you've missed and the game will progress as if everything was in order - until you're completely stuck.
There seems to be no way to get this conversation to trigger in the game after you've progressed past a certain point, no matter who you talk to etc, so the situation is basically irredeemable. But - you can mess around with the files ;)

How to fix it:
So, I know nothing about computers, so there are probably better and smarter ways to fix this, but this one worked for me, and has the benefit of you not having to replay large chunks of the game.
Obviously, making a backup of your save file before meddling with it is probably a good idea ;)

1.) Download the Witcher Save Editor
Download Qst Viewer (You don't really need this tool, but I found it very convenient)
Download KGFF Editor

2.) Open the save in question in the Witcher Save Editor (the readme included with the files explains how to run it)
Click Action->Unpack Save and unpack to the folder of your choice

3.) (Only needed to confirm the problem is indeed the missing Alvin conversation)
Start Qst viewer and open q4003_alvin.qst
Click your way to "on a bank" (pic 1), there are three items listed (Witcher 1,2,3) - exactly one of those needs to be "completed". If none of them are, then yep, that is indeed the problem. You may wanna check the dialogue options displayed for each of the choices, since you'll have to pick one of those in the next step.
Edit: In regards to the "late game bug", please also make note of what it says in the "onCompleted" section at the very top: namely, Witchers 1 - witcher_good, Witchers 2 - witcher_bad, Witchers 3 - witcher_zero

4.) Now, run KGFF Editor and open q4003_alvin.qst . Then click Tools->Search by text "bank" and click your way down until you arrive at pic 2.
From there, scroll down slowly. You'll see some dialogue about the fisher king - scroll right past that, we don't need to tinker with that. Scroll a little bit further down, until you arrive at pic 3.
Now this is where the magic happens. You'll find the three dialogue options further down (each will appear twice), "I told Alvin that no one..." "I told Alvin that becoming..." and "I told Alvin he should..."

5.) Scroll down to the dialogue option of your choice. Above (!) that dialogue option
change value of "Completed" to 1,
change "Marked as True" to 1,
change "CurrPhase" to 0.
(should then look like pic 4).

6.) Scroll down again, underneath (!) the dialogue option of your choice
change "QISDFTP" to 1
change "QuestBegan" to 1
(should then look like pic 5).
In the example in pic 5 I chose the third dialogue option, hence why it states "Witchers 3" there.
Now, save the repaired qst file (don't change the name, obviously).
Edit: If you've skipped step 3, make note of the value of the "OnCompleted"-section - the options being witcher_good, _bad and _zero!

=> And bam, your save is fixed. In qst-viewer, in q4003 the dialogue option of your choice should now be marked as
"completed". Repack the save with the save editor (make sure you've replaced the broken q4003 file with the fixed one).
Start the game, load your repaired save and everything should be fine :)

Edit: Nope, spoke too soon. There is a very annoying bug at the very end of the game, that is quite immersion-breaking but is a direct consequence of fudging the save to complete "Alvin", and I've not found a better solution than the one I'll mention now. Sorry for that, but if there's a better way, I haven't found it (and I've tried a bunch of stuff).
So, we'll move right to
7.) This bug can only be fixed once it has occured. Meaning, during the epilogue of the game, when wandering the Iceplains, you'll talk to the Grandmaster a couple of times. You will at one point encounter the spirit of Alvin who won't talk to you, and afterwards have another chat with the Grandmaster. After having this conversation, save the game!!! since you won't be able to proceed from there. The fix will only work with a save from that exact point in the game, since we're skipping ahead to the next part of the quest which can't be done beforehand or later.

8.) You already have all the tools - open your save file (after making a backup, of course) with the Save Editor and unpack the files to a folder of your choice.

9.) Open q6002_iceplains.qst with the KGFF editor. Click tools->search by text and according to your earlier dialogue choice search for "witcher/good", "witcher/bad" or "witcher/zero".
There are three values you have to change - change Completed to 1
above "cn_gmaster..." change "MarkedasTrue" to 1
change Currphase to zero (should then look like pic 6, attached to[url=https://www.gog.com/forum/the_witcher/need_help_with_chapter_iv_iam_stuck/post18 ] other post [/url]since this one wouldn't have it)
This fix will only work if you're altering the "correct" dialogue choice (the one you picked earlier)!

10.) Almost done now. Save the altered .qst file, replace the broken one with your fixed version, repack with Save Editor, load, play, live happily ever after :)

DUDE YOU ARE MY GOD (BOWS) IF I COULD I WOULD HUG THE SHIT OUT OF YOU (but i wont iam not a homo)
thx you are my savior, if i can do anything for you tell me.
you saved my game, thx a lot, i'll remember that.

it all happend again..... a somewhat of a bug.... dont let me play again.... WHY ME RED, WHY ME.
i need help again, this time its frozen reflections, after killing yaevinn's and siegfrieds spirit (iam going for witcher route)
I talk wtih the grand master again, but it doesn't do anything, i can talk with him again, and he says the same over and over again.
If i try to move foreward, i move throught a little ice bridge, and i have a close on the temple, second later i have a black screen and nothing happens afterwards (i was waiting like 30 mins to see if something might happen but nothing happens i just have a black sreen and i can hear the game sounds, it doesn't freeze if you wanna know).
My frozen reflections quests is in the state after meeting alvin.
i think its all, i don't know what causees this, but it might be my choices somehow broke it, maybe cause iam witcher route? or becouse i have shani as my lover? i dont know but i need your help again, people.
here's my save right next to the grand master.
GOD WHY ME? well i think its better for me than any other person on earth to be bugged like this.