Is there a reason I can not make changes to the skyrim.esm file in test5edit.

For example. What if I changed the damage of a vanilla weapon?

You should be able to edit Skyrim.esm just fine with Tes5Edit--but it might be a lock on the name, perhaps (not tested). What I know is that in the past I have copeid Skyrim.esm, converted the copy to a .esp, and then made edits. The main issue I found was that it could crash when trying to save the full thing, and that cutting stuff out would crash Skyrim itself when trying to load.

I assume if you edited Skyrim.esm, and modified a weapon damage, it would just alter the damage in the game, the same way as if you edit one of the other .esm files.

That said, it's better to use a .esp to change something because this way the change isn't permanent, it's easier to identify conflicts, and you're not going to get Skyrim.esm flagged as faulty whenever you verify your cache.

Any reason you would want to edit Skyrim.esm?

Exactly. You make changes to Skyrim.esm by creating an esp to override (usually with the CK, but other ways exist). Tes5edit just reflects that reality. Even Betesda themselves created Update.esm to do overrides.

I would not delete anything from it and would only attempt to load it in a new game.

When you clean the DLCs you are editing an esm file. What makes the skrim.esm any different?

Skyrim.esm effectively 'is' the game--go move it somewhere, and try to load up the main menu: it CTDs after the splash screen.

There are like a dozen-or-so Forms hardcoded, but everything else comes from a .esm/.esp; presumably there is some hard-coded links within the engine itself to Skyrim.esm to make certain things work (for example, somehow Skyrim.esm can contain Perk Trees/Skills, but we cannot make them--even if we duplicate and edit them, the best we get is nothing; most likely the Engine directly references those Forms somehow.)

With the DLCs, however, they're... different. They're basically just .esp files with a different flag set. The special things they do add (for example, Dawnguard adding Vampire Lord and Werewolf Perk Trees) seem to actually be tied to the Engine somehow-- even if you don't have Dawnguard.esm in your Data fold, you can still view the (empty) Vampire Skill Tree, which you cannot do for any non Skill-tree Actor Values.

What does that have to do with changing some of the variables in the skyrim.esm?

Like changing the damage of a vanilla weapon?

But the DLCs are not esp files the are esm files and can be easily edited in tes5edit.

When I get a chance I am going to back up the skyrim esm file and see if I can do it.

Has anyone else done it?

Curious why this is even a question. Perhaps you should read the EULA that you agreed to when installing Skyrim.

Skyrim.esm IS the software. You cannot touch it.


Open the CK and create a mod, like everyone else. Or, you can use TES5Edit to create a mod by using the copy as override feature. But it must be a mod.

Gosh H, no-one reads those EULA things... (You know, the only stereotype...)

Hmm, now you have me wondering: would that mean we're not allowed to clean the official dlc?

Yes CDM_ it would. The DLC.esms are the same thing as the Skyrim.esm, but I am not sure what I am suggesting violates the EULA

However, Hanaisse may be on to something. That may be why people are always commenting about how you should never touch the Skyrim.esm.

The problem I have is the leveled NPCs. In the cells they have a Level Modifier Tab on their template. When that is checked "easy" even if you mod the list so only the highest level opponents can be selected, they are lethargic bad opponents. However when they are checked hard or vey hard they are smart quick excellent opponents. The effect on the AI is enormous. It would be much easier to simply change that setting in the Skyrim.esm than to change just about every cell with my mod.

I was able to do this very easily by the way. I am not going to say how until I get some confirmation from bethesda that it is ok with them, other than them not supporting a modded game.

I loaded it in the kit. Exact same errors and no problems. Loaded it into Tes5edit no problems no errors. I also checked it for errors in Tes5edit and as far as I could tell they were exactly the same as the unmodded version.

However a strange thing occurred.

The file shrank by about 1500 kb.

Skyrim.esm has records in it that have never been decoded fully. You really should not be editing it. Even if it appears to work now there may be small changes that you can't see that will haunt you later. As was pointed out earlier even Bethesda makes changes through Update.esm instead of editing Skyrim.esm.

What do you make of the file shrinking?

They made the file. If they made it they can easily edit it. Why they choose not to I do not know and no one has yet to offer an explanation.

I am looking to hopefully get something out of this more than - don't do it because it is bad, or something bad may happen but we don't know what or even if it will.

What changes could be made? How could changing the damage of a weapon come back to haunt you?

Well.... no one knows. So I guess, since you're the one wanting to do this, you get to be the guinea pig. Do what you want (after making a full backup of your game install folder) and see what happens when you make the changes you have in mind.

Thank You for the response but we have not heard from everyone yet or even close.

What do you make of the change in file size? 1500 kb

That is quite a bit. Why would it be lost? How could I attempt to find out what if anything was lost?

They are not ESP files with a different flag set, they are subordinate ESMs.

Also, you NEVER EVER EVER alter a BGS game's main ESM directly. You make override record entries in subordinate modules and alter those. That's what the CK does, and that's why TES5Edit won't let you alter the Skyrim.esm; it's hardcoded to abide by this cardinal rule. That module has to be the one constant in EVERYONE's load order for mod sharing to occur.

So the only reason you do not mod the skyim.esm is for mod sharing?

No, because every subordinate module, including the official DLCs, expect records to be a certain way in the central most important module that the game loads.

Why do you want meddle with Skyrim.esm directly when we've already stated how to alter your weapon values properly? Make an override record in a new module, make your changes, and load that module. It's what the CK does automatically, it's possible with TES5Edit.

If your Skyrim.esm is suddenly a different size, you'll need to re-verify the file integrity with Steam.

This has gotten to be a long post. I answered that question.

The problem I have is the leveled NPCs. In the cells they have a Level Modifier Tab on their template. When that is checked "easy" even if you mod the list so only the highest level opponents can be selected, they are lethargic bad opponents. However when they are checked hard or vey hard they are smart quick excellent opponents. The effect on the AI is enormous. It would be much easier to simply change that setting in the Skyrim.esm than to change just about every cell with my mod.

@MadCat,

What's the difference, out of curiosity? (And with that, what would be the difference between a .esp, and a .esp which has the .esm flag set via Tes5Edit?)

We don't mod Skyrim.esm because we don't have any tools that can do so safely and because it's bad development practice that would ultimately lead to far more problems that it would solve.

The very fact that Skyrim.esm unexpectedly changed size is your clue that it isn't like the others and you are headed down a bad path.

The CK we use isn't the same as the one Bethesda uses. It gets altered and certain features stripped out before we get it. It's likely that their original version can edit some of the records we can't but it's also entirely possible that certain core elements in Skyrim.esm are generated and inserted directly into it by the game programmers to ensure that critical features don't get altered by the level designers and others that add content through the CK.

The CK won't let you edit Skyrim.esm and there are record types and options in it that don't appear anywhere else. The TES5Edit team reverse engineers the ESP file format by making changes in the CK and then seeing what it changes in the plugins. They have no way to do the same thing with Skyrim.esm so there are still unsolved mysteries about its contents. The difference between ESP and ESM formats is understood well enough to allow creating and even editing the sort of dependent ESMs found in the DLC but that's not the same as being able to edit the primary game ESM. The thing we can do with converting an ESP into an ESM only allows us to create a subset of the features allowed in an ESM because there are things that can appear in an ESM that can't appear in an ESP and can't really work with those.

Creating an ESP to do what you want isn't that hard. You just need to write a TES5Edit script which locates the records that interest you (which I assume you already have) and then have it save those records into a new ESP and modify them there. Check out the Copy as Override script as a starting point for creating the plugin itself. You'll want to add some conditions so only the records that you need to change get copied and then add the bit of code that performs the edit on the records in the new plugin.

I would agree it is not a good sign but there may be reasons for it.

If I were to do that. The esp would need to change almost every cell in the game.

I would like to comment further on the testing I have done but will not do so until I get some confirmation from bethesda that it is ok with them, other than them not supporting a modded game.

There's nothing wrong with that assuming you load your plugin early. And if you wanted the same effect as modifying Skyrim.esm you would want your plugin loading as early as possible so other mods could choose to override it.

There's no real advantage to what you're proposing other than potentially having one less entry in the load order. The number of records involved is rather small compared to the total number of records the game processes. And getting information out of Bethesda is a rare event so you might be waiting a long time.

Frankly it's your game so you can do what you want, but Bethesda would absolutely not allow you to distribute a modified Skyrim.esm. So if you are thinking of actually releasing a mod for others to use you only have one choice unless you're planning to provide some program or TES5Edit script that users would have to run to make the changes in their own copy of Skyrim.esm. (And I would strongly recommend you not try to encourage ordinary players to modify their Skyrim.esm because they will inevitably do something wrong and really mess up their game.)

We don't do that because the mod would work for you alone

Even if you were able to alter skyrim.esm, two mods that alter it won't ever be able to work together because only one instance of skyrim.esm can be loaded.

No idea what this Level Modifier Tab on cells is, (I don't see it?) but it sounds like you're talking about Game Difficulty Settings. These settings can be changed under Gameplay > Settings. Filter for fDiff and you'll find;

fDiffMultXPVE (very easy)

fDiffMultXPE (easy)

fDiffMultXPN (normal)

fDiffMultXPH (hard)

fDiffMultXPVH (very hard)

Each setting has a value from 0.5 to 1.5 and choosing your game difficulty in options sets the tone for NPC difficulty. You could try playing with these values.

When you open a cell in the creation kit and you see the large letter Ms, those are the leveled NPCs. Some are Green, Yellow, Red etc.

If you edit one of them you will see a level modifier tab for that NPC.

"The problem I have is the leveled NPCs. In the cells they have a Level Modifier Tab on their template"