Couldn't upgrade to High Sierra

Hi nottp - I had a similar problem during my first attempted install. I would recommend restarting your machine into "Recovery" mode by pressing Command + R when restarting the computer. This will take you into a menu where you have the option of installing Mac OSX.

When you boot into recovery, it will take a few minutes. Make sure that you sign into your wifi network and then when you come to the main menu, you can select the option that says "Install Mac OSX." As long as you have the High Sierra installer downloaded onto your Mac, it should give you the option to do the install of High Sierra. This worked pretty well for me.

Sorry to hear this did not work. I would try two things:

1) Restart your Mac back into Recovery mode and then use Disk Utility to perform "First Aid" on the drive where you want to install High Sierra.

2) Delete the copy of the High Sierra installer that you have and re-download a fresh copy of the installer from the App Store. Try your install again.

Sorry this is not working and hopefully we can get you back working again. The disk first aid should help though.