So after a month or so I reinstalled Skyrim and got all the mods I wanted, installed them with BAIN, made a Bashed Patch etc. Eventually the game was ready to play and I got in.
Everything seemed fine except for general Tullius (and later Hadvar) being half-stuck in the ground during the execution. At that time, I thought it wasn't a big deal. Everything else went like it should until I entered the Helgen keep with Hadvar.
Inside, I saw http://dl.dropbox.com/u/35436007/ScreenShot4.jpg. There was almost nothing after this room, http://dl.dropbox.com/u/35436007/ScreenShot3.jpg with some other parts of the level far away.
I reloaded the autosave and the keep looked fine now. Until Hadvar tried to get to the room with Stormcloaks. He stopped halfway in the corridor and refused to move forward, no matter what I tried (console commands as well).
At that point I knew there was something really wrong with the game and decided to try unchecking the mods etc. Hadvar was still stopping at that point even without any mod loaded.

It seemed like he was already bugged in the save. I started a new game without any mods. Got to the part right before entering the Helgen keep and saved (everything was fine). Hadvar got through that point like he should and everything was ok.
I tried it with all mods loaded. After entering the keep the blue void was there. I was happy - I had a save suitable for checking which mod was messing up.

Now it gets strange. I was unchecking each mod until I found the one that was messing up, and I found it. But I decided to try and run the mod alone to make sure it's it and not some conflict. I was slightly surprised to see it worked fine.
Now I started checking all the mods again to find out when will it stop working. When I found the second mod, I tried the game with only both of them active. It worked fine again.
The process repeated a few times. After a LOT of time and game restarts, I think I have found them all.

Now, the strangest thing about that is that all of the mods have to be activated for the bug to happen. If I disable even one of them, the bug's gone.

The list:

Now, the solution for that seems to be really easy - just disable one of them. I think this is really strange though, the mods don't really seem to be related at all and it looks like they trigger some kind of engine bug. For some reason they completely break the game when together.

I repeat, the bug is always there when all of these mods are enabled. It doesn't matter if they're the only ones or if there's more mods.


Anyway I thought that was interesting and hope maybe some of you have any idea why would this happen - the mods don't all seem to be related. Most of them are relatively large though. I might have triggered a really specific engine bug.

This is on patch 1.5.26. Doesn't matter if I run it with SKSE or without.


TL;DR version - Bug occurs with specific mods loaded, doesn't if you disable just one of them.


PS. I wish we had TES5Edit. I could check what the mods have in common and I don't seem to be able to do it with the tools we have right now.

I have seen the same issue, usually when I start a new game, the first interior I load has that bug. Only thing I have in common with your load order is unofficial patch and no mercy. However, I am betting the problem is with the game, not the mods.

Same issue as this: http://www.gamesas.com/topic/1362421-falling-through-the-floor-in-dark-brotherhood/

Definitely something afoot out there in modland lately.

If, in a PM, you can link me to an archive bearing only the plugins in question, I can load them up in FO3Edit/Filter/Screencap conflicts, for science.

Are you using Horse Fast Dismount? That's usually the mod associated with Tullius getting stuck in the ground.

I am using that, thanks! I was a bit worried about that because it happened even after I removed one of the mods.

It seems that esmifying one of the mods apparently fixes the bug. I've got a different load order now, I don't have half of the mods I've isolated before, but I've got new ones causing this. Anyway, after getting Sounds of Skyrim esmified the bug didn't happen (it wasn't the "blue void" this time btw, the two chests and light sources on the left of the room were missing - it still happened every time with certain mods loaded).

A few days ago I've seen someone writing about some kind of memory limit for .esp files, can't find it now though. Seems it's true. Has anyone got some more info about that? Was Bethesda informed if the memory limit thing is true and we now know what causes the bug?

I've seen a lot of comments on certain mods about problems similar to this one and the mod authors can't find the cause - because there isn't anything wrong with their mod - but it sure does seem like it's their fault (the glitch doesn't happen when the mod gets disabled). This causes a lot of confusion to modders and the mod users, the mods get accused of being buggy while they're probably fine.

That's because some people do not understand the issues of complex systems interactions. There are academic fields of research that study this topic in various forms and different areas. My own current field, technology studies, is one such area. People who understand complex systems and their issues may point out a problem, but they'll normally mention that it may be a particular mod or it may be some form of interaction with a mod, other mods, the official software, and their specific hardware and software setup. Basically, there are many other elements that could be the cause of the problem or rather there are many interactions that could be the actual cause. Still, it's important to inform mod authors because the problem might only be their mod(s) and they won't know to check unless they are informed.

One good example: there are people who think that the USKP is bugged. Very unlikely, but there are people who believe so, anyway.

Another example: I and some others have experienced odd CTDs with both SkyTest - Realistic Animals and Predators and Real Wildlife - Skyrim. Deactivating the latter stops the CTDs, even though we didn't see them earlier with both mods active. However, since we are trying to actually play the game, we simply report the experience to the authors and the community, deactivate RWS and play without it. Our reports might save days of grief for other players if they experience the same issue (because it took days of testing to discover a way to solve the issue for us).

The difference here is that mods in your example change similar things - both deal with wildlife, leveled lists, AI and things like that. There's a high chance for conflicts with two mods dealing with similar things, both of them being huge and overhaul-ish.

But the mods I'm talking about are usually completely unrelated and don't even touch the things that break because of that glitch. (Soul Forge - a house mod that has no entrance - you can only teleport inside and the only thing outside of that - in the vanilla game - would be a book that adds a teleport spell. Birds.esp - it adds more instances where you see birds in the game. I really doubt they could conflict in any way - and they do trigger the glitch with some other mods)
That's why I wrote about that glitch being so bad for modders and mod users - if it's really this one, it's going to confuse the hell out of everyone because there isn't any reason this should be happening - it's not the modders' fault.


I do realize you're not really talking about this glitch, but about not understanding complex systems, and I agree with you about that. Just had to clarify why this one issue is really bad and confusing for modding - it just simply doesn't make sense.

EDIT: Look at these 3 posts:
http://forums.nexusmods.com/index.php?/topic/595514-quest-the-bigger-they-are/page__st__10__p__4810549#entry4810549
There's a lot more issues like that I've seen in comments about other mods as well.
And yeah, I'm pretty sure that mod is a "trigger".

The glitch doesn't affect a specific place. The engine just seems to fall apart and not load some parts of the game etc when it happens.

Had the same problem with Abandoned Prison. First I thought it was either SoS-Dungeons or Interesting NPCs since both edit that cell. But to my surprise deactivating any random mod from my load order made the bug disappear.