Same problem here!
Installing the Visual C++ 2012 Redistributable did the trick. Great that I found this post, and super that Juanjgon cracked it! Still works after more than 4 years
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Concidentally, went from an i7, NVidia GTX 670MX laptop to a newly built !9-16 core, 1080Ti desktop, to make the most out of the Octane plugin.
Originally, I had copied over my .newtek and plugins folders from my laptop. I then got an error upin starting LW that said there was a failure to load the Octane Master plugin.
I uninstalled, reinstalled everything cleanly, and tried adding the plugin manually, and then got the error that led me here.
I have LW2018, but still have to use 2015 for Octane, so I am eagerly awaiting the LW2018 Octane plugin!!!
Cheers
Johan