After exporting my geometry in my scene to obj I received an error stating that the file had a Rats Nest. Does anyone know what could be causing this error? Could it possibly be a corruption in the file?

I wish I knew, Ryan…
I’m posting this reply because I have this problem too. Nothing anywhere in the docs addresses this (unless I completely missed it), so hopefully someone out there can shed some light on this for the both of us…

Thanks Salaros. Any way to prevent that? In my case all I did was import an .OBJ (no warnings), move some vertices around (none removed, added, scaled, or seriously touched/warped otherwise) and try to export that as an .OBJ again. Seems to me there is no reason for what I’ve done to corrupt/damage the .OBJ in such a way that it would throw this error. Unless it already imported that way, but doesn’t give a warning then..? Is that even possible?

What happens if you import the object then immediately export it without changing it in any way?

Max 4.2 through 2013.
XP-64 (SP2)
NVidia 9800GTX-512 (Driver 266.58).
Core 2 Quad Q6600 2.4GHz, 8Gb Ram, DX9.0c.

Had this issue too… assumed it had something to do with overlapping verts… but after hours of checking and fixing overlaps I get the same error.  Tried with two similar bipedal models, both created in Max, exported to zbrush (where I discovered the overlaps) and exported back to Max.  Neither has any overlap now, but one imports/exports with no errors and the other one has “rats nest”.  No ideas.

*edit* So I found a few unwelded verts in the model that was giving me issues… once I fixed these and exported again (a few times) I no longer got the error.  I would get random holes in my model though when bringing it into zbrush, but I found that deleting the nearest polygon and extruding/welding a new one seemed to fix this…

So try checking your model for loose vertices.