In general, what causes pure virtual function calls to happen?

[johnbturnip]

I'm not trying to fix any specific occurrence of this error, so don't ask me for my load order.  Rather, I'm curious as to what causes Skyrim to have this error. Obviously it happens when a mod-maker makes some kind of mistake, but exactly what kind of mistake causes it?

 

Does it happen when a mistake is made is made in Papyrus?  If so, what's an example of a papyrus script that would trigger it?

Does it only happen when external, non-papyrus code is being run?(For example: SKSE or ENB)

 

When I'm making a mod myself, what would I need to do to avoid causing this error?

[aim4it]

It normally comes from external/injected code.

[WraithSlayer]

Obviously it happens when a mod-maker makes some kind of mistake

 

Not necessarily. Some base functions are just prone to exploding the game under specific circumstances, even if the modder isn't doing anything technically wrong. SetScale is one of these, which occasionally causes the SexLab framework to crash Skyrim at the start or end of an animation. (more info about it here if you're curious)

[darkconsole]

the only pure virtual function call error i have ever experienced came from dawnguard - if you go into the soul carine and pick up one of jiub's pages and then leave area without finishing that quest, you will experience this once every 20 minutes. i believe this particular error is caused by the game's scene manager, which they have an npc randomly roaming until you finish the quest as there is nothing in the papyrus that i can find that should be doing anything that terrible. the only thing that quest does is kick off his scene after you pick up the first page.

 

at its core a pure virtual function call error is more or less trying to call a method on a non-initialised or missing object or something to that effect. from papyrus its not really something you have to worry about. your errors will manifest as simpler things in the papyrus log "attempting to call function on None" - pure virtual functions are basically abstract and without their runtime implementation zonk out.

 

you'll only have to really deal with this if you do an skse plugin.

 

i've never seen the setscale thing manifest a virtual function call error. that one flat out just punches the engine in the face and sends me back to the desktop without any clue.