Skyrim: Fixing Navmesh Deletion Using TES5Edit
The CK reports errors similar to this:
The errors will be listed in the EditorWarnings.txt file in your Skyrim folder.
1. You deleted a vanilla navmesh using the cell window in the CK.
2. You accidentally merged two navmeshes the CK listed as islands.
In either case, if the error being shows is consistent, you have a vanilla navmesh that's been deleted.
This can be fixed relatively easily with TES5Edit. Note the cell(s) being reported in the warnings file. You'll need to track them down.
The easiest way to go about this is to open the CK, find each of the cells you're working with, and gather up their form IDs. You can get the form ID of a cell by hovering over the name in the left hand side of the cell window.
Keep the CK open and load the file in TES5Edit. At the top left is a box to search for form IDs. Enter one of them into the box and press enter. You'll be taken to the location in Skyrim.esm where the ID exists.
CTRL+Left Click on the name of your cell in your file and you'll be taken to the location in your mod where the form is edited.
Expand the tree so you can see your navmesh data listed.
In the CK, look at the form ID for the navmeshes. This is going to take some knowledge of what you've done and will be the hardest part of all this. In the case of the Pinewood example, you want the very first one that shows the largest number of triangles.
In TES5Edit, note the form ID highlighted in yellow that starts with 00. Notice in the righthand pane it is listed as deleted. Write this form ID down.
Now on the left pane, right click on this entry and select remove. You will be warned to think about what you're doing. Say yes, and you'll get a second prompt asking if you're sure this record is the one you want to remove. Say yes again. You should be seeing something like this now:
Now right click on the form ID for the navmesh you want to fix (in this case 01022CC9) and select "change form ID". When asked to input the new ID, replace it with the ID of the vanilla navmesh you just removed (in this case 000F26C0). After pressing enter, you maybe presented with a box that looks like this:
Right click on one of the entries that's showing and "select all", then hit OK. This box is asking this because other records refer to the navmesh and need to be updated so they match. You'll get a second prompt saying they were successfully updated. Hit OK again. It's this phase here that the CK doesn't handle correctly when removing navmeshes via its own details screen and results in the CK crashing trying to reload the mod. It doesn't update all these records properly.
Congratulations, this navmesh is now fixed! If this was the only one you needed to correct, you can close TES5Edit now and save the file when prompted. All of your data will be perfectly preserved but will now be editing the proper navmesh.
If you have more navmeshes to fix, repeat the procedure for those as well. Once you've done a few of these it will become a lot easier to deal with. Ideally of course we shouldn't have to do this at all but at least now it can be done safely.
"It is pointless to resist, my son." -- Darth Vader
"Resistance is futile." -- The Borg
"Mother's coming for me in the dragon ships. I don't like these itchy clothes, but I have to wear them or it frightens the fish." -- Thurindil
Well. I guess that's that then.
1) I have never had any problems (or had reported problems) with my MOD from this issue. Other than the CK squawking (and me hitting "yes to all" on the ignore option), what problems could happen if I just leave these be?
2) I have extensively modified the navmesh in certain cells - I put a fortress there and at the time, the TESV Alliance tutorial advocated deletion of navmesh where your buildings were and re-mashing as necessary. My redoubt takes up nearly a whole cell+. Because of this I am worried about inadvertently fouling up my navmesh if I attempt this procedure. What exactly is this procedure doing? Deleting the record for a deleted record and re-labling your modified navmesh to the record ID of the vanilla one? I want to make sure I understand WHAT I am doing in addition to your excellent tutorial on HOW to do it. THANKS!
There's a difference between deleting an entire navmesh and only deleting some triangles in one. The TESA tutorial is correct that you need to remove any triangles your additions obstruct, but you should take care not to delete more than is absolutely necessary. Then edit what's left to fit things better.
In your case, it sounds like you'd need to remove substantial enough portions of the vanilla navmeshes to cause problems since you'd probably end up deleting one entirely. In cases like that it's best to take the vanilla navmesh, select all the triangles for it in the cell you're editing, and drag them all skyward so that they're out of your way while you work. Leave them there when you're done making your new navmesh. It's not the most ideal solution but it's also the only one that will work to avoid generating CTDs from deleting one.
If you can manage to edit the area without causing a deletion, that's best, even if you have one vanilla triangle left in a cell.
The procedure outlined in the guide is geared toward fixing a vanilla navmesh that's been deleted because the CK changed the form number on it during editing. Not toward one that's been intentionally deleted - though again, never do that.
I use TES5Edit version 3.0.26 EXP.
According to your description, "Now on the left pane, right click on this entry and select remove.".
But "remove" does not exist in the right click menu in the left pane. Instead, "remove" exist on esp file name " Pinewood Village.esp" in the right pane.
And right click menu does not have "change form ID" in the entry of left pane.
Where is "change form ID" in right click menu?