FumeFX (v2 - as yet unsupported) + PRT FumeFX01 with no particles present, causes a Krakatoa error at render time, add FumeFX object as the source and then hit render in Krakatoa.
See image:
Mike
This is EXACTLY what is unsupported about FumeFX 2.0 - they changed the arguments of the getPath() method and we have to pass the right argument to make it work. (Krakatoa uses an internal MAXScript call to get the location of the Fume cache - if this was a problem with the MAXScript side of Krakatoa, I would have fixed it, but it is in the C++ code).
Once we get our FumeFX 2.0 installed in-house, we will fix this and stuff will probably start working.
That being said, thanks for the bug report! Next time, please post it to the Bugs forum.