the wim file is from windows pe 3.0 Version: 6.1.7600.16385
tried using windows 10 as the host failed as well
seeing as dismapi was introduced in 8.0...
Does that mean that servicing a windows 7 wim is also unsupported or should it be downwards compatible?
try and report the result of the below.
I am using a win8.1 host using the system dismapi.dll against boot.wim coming from a windows 8.1 install kit.
You should (although i may not have tried) be able to process a win7 wim file from a win8+ host.
Note that it does not mean you cannot use dism on win7 host : it is just another dism architecture (i.e it does not use dismapi) and it is likely that you will have troubles processing new wim files on a win7 host.
If you are really into using a straightforward wim tool, use the excellent wimlib .
tinydism_cmd.exe /get-imageinfo c:\temp\x86\iso\sources\boot.wim
ImageName:Microsoft Windows Setup (x86)