Only when it is properly set, Multiwfn can directly load .chk file by automatically invoking formchk; otherwise, you should manually convert .chk to .fch/fchk by formchk, and then use Multiwfn to load it, because Multiwfn doesn't natively support .chk file.

I am using the multiwfn version for windows, in the new manual is not clear how to define the paths. I am trying to convert a .chk to .fchk file. If I put the path of the file with extention .log or .out I do not have problem but I can not get bindind energy, instead if I tried the path for the .chk file I get the following message: "formchk.path" parameter in settings.ini has been defined, the formchk executable file cannot be located, therefore the .chk file cannot be directly opened by Multiwfn.

My files are calculated with gaussian09 and gaussian16