Recovery Bootable USB

New2Day Said:

"Recovery Bootable USB:[....]I'm trying to create a bootable usb to reinstall High Sierra OS on an old iMac 27inch. I have wiped my iMac and tried to reinstall in the macUtilities (reinstall macOS) which doesn't work it fails to find the server.[...]"

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Using a USB Bootable Installer:

A. Create it on Another Mac:

Use a Mac that already has the macOS installed, as a way to create this USB Bootable Installer. Go here: Create a Bootable Installer for macOS - Apple Support

B. Mount the Drive:

Boot into Recovery Mode (Hold Down: [Command + R] upon boot). Then, using Disk Utility, see if the Hard Drive is seen. If it is, then see if you need to click the “Mount’ button for it. Try rebooting once more. If of no success, then click unmount button, and then the mount button. Try rebooting once more.

C. Connect to the Internet:

While in Recovery Mode, look on the top-right corner of your screen, and see if you need to connect to WiFi.

 Start up from macOS Recovery

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

In Disk Utility>View, select Show all Devices, highlight the top left entry.

APFS won't work for Sierra or earlier, Sierra or earlier needs MacOS Extended Journaled. High Sierra won't work for APFS on earlier Macs.

What has often worked for others is to use this Restore Method instead of CMD+r keys...

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

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New2Day Said:

"Thanks for the hints… I can access the drive on the old Mac and the wifi works … I’ve tried to create a bootable usb on my MacBook Pro without any luck so far"

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You are welcome.

Try Ethernet:

Be connected to the internet when creating it, and have the macOS installed. If you have Ethernet, then conservative using that for your method of connection. IF there is no Ethernet port, then use an adapter like this: The Belkin USB-C to Gigabit Ethernet Adapter - Apple