Unable to install High Sierra

Well it is a mystery, I am at a bit of a loss you could try asking the same question over here, iMac in case someone has come across a similar problem on the same hardware.

Did the Apple Retail Store say what they meant by purging the hard drive.

So the white circle with the white line through it is a sign to say the install could not find a valid file system. Before doing any upgrades or OS updates it is wise to run Disk Utilities First Aid to check for any directory/ disk errors.

However you managed to restore your mac to Sierra, so hopefully you will now be able to install High Sierra.

Before you upgrade please check that any third party apps you use are compatible with High Sierra, https://roaringapps.com/ and also check to see if any printers/ scanners or other hardware you use with your mac has updates to drivers or software available for High Sierra.

High Sierra should install on a fusion drive, it just won't be able to use the APFS file system so will just keep the HFS+ filesystem we've all been using for years.

Can you have a look in your Application folder fo Install macOS High Sierra.app, make sure it is about 5.12Gbs, if you find it you could then download this, http://diskmakerx.com/ and make a bootable USB installer. This will ave you having to keep on downloading via the App Store. If you can't see the installer app you will need to download from the App Store once again, when the installer starts just quit and then make a copy of the install app and the bootable USB.

One booted from the USB select Macintosh HD (or whatever you have called your Sierra disk) and see how it goes.

Well that is very puzzling indeed, I can't see why Sierra can install but High Sierra won't.

I take it you are trying to install over Sierra or are you wiping your disk and then attempting to install High Sierra.

If you are doing a 'clean install' remember to format your disk as HFS+ Extended (Journaled) on a GUID partition.

So was that an Apple Retail Store or just an Apple authorised reseller?

I find it strange an Apple retail Store would charge you fo installing an OS.

If you are now back to Sierra you could download this and run it on your disk, there is a free trial. https://binaryfruit.com/drivedx

I had something similar happen and was able to fix it by restarting in recovery mode and reformatting my hard drive. That symbol usuay means that your computer can’t find an available hard drive. Most likely, either your hard drive was not formatted correctly or it was not mounted.

I have an early 2011 15” MacBook Pro. It had some main board parts replaced a couple years ago in the unofficial hardware defect that caused solder connections to fail over time from heat stress. When I apply this latest OS upgrade, it fails and causes a no boot situation as described above. I have to restore from a TimeMachine backup to repair. Any suggestions? I’m assuming the firmware of whatever hardware got replaced is the source of conflict.

But you've tried that before haven't you.