I am running the version 1.9.1 on Windows Server 2012 R2 and I have installed the ImageMagick-7.0.5-10-Q16-x86-dll.exe (https://www.imagemagick.org/download/binaries/ImageMagick-7.0.5-10-Q16-x86-dll.exe). However it says that the executable cannot be found. I think it's looking for "convert.exe" which no longer exists. Renaming "magick.exe" to "convert.exe" got around the issue but when I upload images it fails to crop.
Yeah, simple solution is to use a version 6.x of ImageMagick....