I'm trying to upgrade to High Sierra on my 2014 iMac and consistently get a "could not unmount the volume for repair..." message. Apple support and I have checked everything regarding the Mac and the fusion drive, and Apple support thinks the problem is that I have VMWare with Windows 10 installed. Has anybody else had a similar problem? Has anybody else been successful installing High Sierra with VMWare and Windows 10 already installed?
Thanks!