The situation is probably well known:

I have downloaded a mod that uses Update.esm as a master. The mod in question adds another room in the basemant of Proudspire manor.
But after Patch 1.5, I get CTD's whenever I exit and re-enter Proudspire manor.
I already pinpointed the cause of the crashes to that mod, by doing the following:
* De-activating all other mods still CTD's the game upon re-entry.
* Using a new character in combination with the above also results in CTD's.
* De-activating the mod allows me to exit and enter Proudspire as much as I like.

A quick search through multiple forums told me that this crash problem is caused by a Navmesh problem.
My question is: Can I fix a mod that is plagued by this issue? If so, how do I do that?

I contacted the creator of the mod in question, and because he has not much free time, he gave me permission to sort this problem out, so I can update the mod accordingly.

Thanks in advance

At this time it is doubtful. The problem is being heavily discussed here http://www.gamesas.com/topic/1358688-navimesh-bugs-2/page__fromsearch__1. Since it is a problem introduced in the latest patch, and no work-around has been found yet.......you may be wasting your time.

Ah, ok. So its basically waiting for someone to find a solution, then.

If you UL/Link it, it's possible I could fix it with an ONAM list, but you'd be locked out of it as the CK won't set it as "Active" with its ESM flag on. Worth a shot for science?

Whats an ONAM list?

http://i.imgur.com/VaIrx.png It's discussed more thoroughly in the aforelinked thread.

The link to it is below. One warning, this mod can be considered semi-NSFW to some, as it adds a room with working wall-shackles to Proudspire. (But reasoning like that would also make the entire game NSFW, as the Thalmor basically have the same thing.)

http://skyrim.nexusmods.com/downloads/file.php?id=12189

If you succeed, can you tell me how to do this myself so I can try to temporarily fix other mods encountering the same problem?

http://www.mediafire.com/?qsaufy4x97xbcxv with some stuff in the ESM http://i.imgur.com/y2hmj.png.

Oh, you'll probably want to change the voices folder to the ESM's name as the INFO's are all [02]'s

If you don't want to go the ONAM list, delete ALL (and I mean all) of the navmesh info with TESVSnip and redo it manually.

Not fun, but it will work.

All navmesh info. Is that all NAVM records, and the NAVI too?

i've tried that. it doesn't work for me

What do you mean? I only know the basics of the CK and some basic NifSkoping, nothing more. Sorry
But still thanks for helping

Tried this, it doesn't work.

The new beta for 1.5.26 reverts the changes they made to navmeshes. We still have all the old navmesh problems but this should at least take care of the CTDs.

Yep, CTDs fixed, but all navmeshes in-game are broken as they were in 1.4. Which I guess is tolerable if your mod has a small enough navmesh for this to go unnoticed

Indeed, I will contact the author that the problems are fixed. I am glad Bethesda took relatively swift action.
But thanks for your time

I've been building my own dungeon mod and been able to test it fine up until the latest 1.5.26 update. Now when activated, the game CTD before the main menu even loads. I can't even test it now. Should I go through and remove all nav meshes and do them by hand?

If you don't want to go the ONAM route, just rename the esp from housemod.esp to housemod.esm. Open it up in the CK, set as active file, save it. CK might crash. Should still work. Will resolve any navmesh issues, for the most part.

this only works if there are no vanilla navmesh edits. from my understanding, if an esm is editing records from another esm (such as skyrim esm), it needs ONAM

Was able to test it. Thanks for the advice. but from this point on, I'll have to edit the esp, then convert it to esm when I want to test it? does that sound about right? I'll do some research on ONAM for a longer term solution. Thanks all!

Hmmm...Deus Mons edits vanilla navmesh around a portion of the exterior and it uses both esm and esp files....AI seems to work fine. Perhaps I'm not editing enough of it?