Troubleshooting Introduction

This is a collection of articles on troubleshooting TES IV problems -- gotchas, common mistakes, CS bugs, etc. The basic ideas and topics were originally discussed in this ESF thread.

These topics could be organized in a lot of different ways, but for now we can start with a simple list.

I've created it as a category so we can add more specific topic articles in the category.

What follows is essentially a long list of some common mistakes and their effects on players and/or the CS. Please suggest more ideas if you can.--Dev akm 17:56, 20 February 2007 (EST)

Debugging

When something just isn't working right, look here for possible causes.

Comma Instead of Period

This can cause severe headaches for the scripter: The compiler will accept a comma in place of a period in reference syntax, but the script will silently fail in the game when the line is encountered.

 player.modAV health 200 <- Fine
 player,modAV health 200 <- Suddenly your script is no longer running and you're wondering why

Easy to miss when you're looking for logic errors.

Numerals

Don't start an ID or variable with a numeral.

 short 5forFighting; BAD
 long benFolds5; GOOD!
 myGuy.moveTo 0marker; BAD

Mismatched If/Endif

The compiler will ignore extra endifs when you save your script, but they can cause the script to stop running when encountered during gameplay. Make sure each if in your script is paired with exactly one endif:

if ( something == happened )
  do something
endif ; GOOD
endif ; BAD, extra endif may cause errors in the game

The best way to avoid this problem is to use proper indentation of if-blocks.

Quest Topic Scripts

The Scripting section in the Quest/Topic editor seems to be for very generic scripting like setting global variables and doing things like setstage. Be aware that while some things may compile clean here and seem perfectly fine, they just don't work in-game.

Getself != player

Be careful if you use:

 Getself != player

When called in a scripteffect spell, the statement sometimes evaluates true for the player. The easiest solution is to add another condition to double-check it, such as:

 getdistance player >0

However, getDistance is unreliable if the player is swimming. The best solution is to use:

 ref refVar
 set refVar to getSelf
 if ( refVar.getIsReference player == 0 )

Performance Problems

This section is intended as a place to list performance problems and tips, especially those related to scripting.

Gamemode Scripts

Avoid using gamemode scripts wherever possible. Use quest scripts if you can, or try to find ways to put as much of the script work into OnLoad, OnEquip, and ScriptEffectStart blocks as possible.

If you need to use a GameMode block, use an 'if' test or a flag so the code will only run when necessary. For instance, if you need to run an item script whenever the player hits a switch, place this on the switch:

scn YourSwitchScript

short Working

begin onActivate
  set Working to 1
end

and this on the item:

scn YourItemScript

begin GameMode
  if YourSwitchScript.Working
...
  endif
end

CPU-Hungry Script Functions

Generally, scripts have little affect on FPS, especially compared to graphics. However, if run every frame there are a few functions that will cause a noticeable (>1) drop in FPS:

1. GetSecondsPassed
2. GetNumItems (OBSE)
3. GetInventoryObject (OBSE)
4. GetFPS (OBSE)
   • However, you can run this every few frames without a drop. This is most useful as an alternative to GetSecondsPassed as ((Number of frames passed) / GetFPS) approximates the amount of time passed.
5. GetDistance
   • I have tested the others above, but not this one. However, I have seen it mentioned several times that GetDistance is a CPU heavy function, so I'm including it here.
   • --Haama 17:54, 10 September 2007 (EDT)

Note that for all of these, they are incredibly fast functions. Even the slowest, GetInventoryObject, can be run 1000 times and the next frame will come up in less than a second. They will only cause problems if run them constantly (every frame or so).

The main problem with CPU-hungry scripts comes from Oblivion's "brick-wall" for FPS and script processing. Scripts won't touch FPS until you hit a certain limit, and then even a few extra small scripts can start dropping FPS.

See Code Optimizing for more details (in planning/progress).

AI Overload

If you use advanced AI on a lot of NPCs or creatures, the game may start to suffer from so-called "AI overload", causing NPCs and creatures to fail to process their AI as you approach them. This can do nasty things like giving roadside bandits a lobotomy -- they just stand around and do nothing as you approach.

Creatures that are swimming seem to put an extra large burden on the system, possibly because the pathfinding is trickier in the water?

Low-Level Processing

Avoid low-level processing for as many creatures and NPCs as possible. Use the "No Low Level Processing" option to keep them from processing their AI unless the player is in the same cell.

Obscure Problems

These issues don't occur very often, and we don't even really know what causes them, but they hurt nonetheless.

Pathgrid CTDs

Does anyone really know why the pathgrid CTDs happen? The last thread about it I remember didn't find a solution.

This is an older problem that plagued both UL and OOO for a while. Basically, changing pathgrids is risky and requires a lot of testing to avoid CTD issues. I didn't find any surefire solutions for this either. Does anyone know if this topic has been written about in any more detail than the introductory Path Grid Generation article and Path Grids (simple)?

Black Screen Bug

This is the Infamous Nvidia + HDR Black Screen Bug.

This bug can usually be fixed by the mod-creator. It is usually caused by problems in a custom mesh. This can happen if the mesh creator forgot to assign a valid material to part of the mesh. It can also happen if you have an opaque texture assigned to a transparent portion of your mesh. It can even sometimes be caused by a standard shader like the GhostEffect.

It can also usually be solved by updating the tangent space of certain mesh nodes in a .nif file. NifSkope has a spell to do this.

Once you've narrowed down which .nif is causing the problem, simply open it in NifSkope, right-click each NiTriStrips/NiTriShape node and select Mesh -> Update Tangent Space. This works most of the time.

Related Articles

Helpful Programs

TES4Edit
Wrye Bash
TES4Gecko