Unspecified Error when Trying to Install macOS High Sierra I have a Mac Mini (Late 2012) and a MacBook. About a week ago, I suspected that my Mini had been infected. So disconnected the Time Machine to preserve my backups, switched to the MacBook and when I had the time, downloaded the installer and tried to install High Sierra. 

I created an external bootable media by downloading the installer on my MacBook, plugged in an external HDD and ran sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MacInstall

I got to the screen with the utilities, started Disk Utility and erased my Macintosh HD and replaced it with APFS.  But of course, it's not a solid state drive, so that failed. I erased the disk again, and reformatted it as HPFS, journaled.  

This time, I get 'an error occurred while preparing the installation. Try running this application again'. 

I have downloaded the installer a second time, and tried again. Same result. I checked the date and it is correct. I even tried resetting the NVRAM. No luck. At this point, I have a Mac sitting here like a brick, that I can't use. 

Can someone recommand how to get round this?
The most likely error is that the disk isn't partitioned correctly. If you have a bootable installer or can connect it in target disk mode - try erasing the entire physical volume again.



In the image above - you want the top item selected and not the volume under the physical drive. I like to click erase and then not make any changes from the defaults - leave the name Untitled or whatever the default name is - not Macintosh HD.

Then when the installer runs, you might need to look at the install log (press command 3 and command L when the install starts) or we'll need to chase down where or if your installer is saved to disk after the install aborted.

In some newer hardware - you need to be connected to the internet with no firewalls so the installer can go get the components for the hardware - perhaps that step is failing and the install log would likely show that.

Here is Apple's full steps on the erase - so choose it over my steps above if mine fail you.


https://support.apple.com/en-us/HT204904