Its not an error message per-say, its a warning message saying that you (via some settings) requested Krakatoa to use the FumeFX fuel/fire channel but it wasn’t actually present in the file after using the FumeFX SDK to load the file. You can likely ignore it, but if any of your Magma flows depend on the FumeFX fire value being there they are not going to work.
I see you are using the out-of-date Krakatoa 1.6.1. Version 2.0 explains these warnings using words instead of hexadecimal values so its somewhat easier to work with.