Help Installing High Sierra on 2010 iMac

I have a mid 2010 iMac (21.5”) with a fresh SSD in it. I’m trying to install High Sierra on it. I have a high sierra USB drive made. When I boot up the machine I’m brought to a screen that rotates between showing an image of a mouse or a keyboard. The pictures presumably ask me to turn on a mouse or keyboard. I can’t get past this screen.

I have a trackpad and an Apple keyboard powered on and in pair mode. I can boot the iMac into Target disk mode by holding down the “T” key on that keyboard. That proves the keyboard is talking to the iMac.

I’ve tried connecting the new SSD to my iMac running Catalina in an effort to install High Sierra onto the SSD. But, my Catalina iMac won’t run the high sierra installer.

I’m stuck. Any ideas?


Definitely need to get a new installer if you haven’t made it since October.

Good advice about using a recent installer. I know my installer is old.

Now I’ve got a new problem. I can’t download the High Sierra installer. On my Catalina iMac, when I click “Get” on the high sierra download, the App Store opens up my system preferences system updater and then tells me “Update not found.”

If you have a suggested work-around for this issue I’d welcome your wisdom. In the meantime, I’ll try booting while holding down shift-option-command-r.

Thanks for the input!

I booted up with shift-option-command-r. That gave me an animated globe on the screen. Once I got on my network it gave me a progress bar. That finished and it booted to the same “mouse/keyboard” screen. So it seems I’m back where I started. :pensive:

Try this in

softwareupdate --fetch-full-installer --full-installer-version 10.13.6

In Catalina, that should download the High Sierra installer.

Running that in terminal gives this result:

softwareupdate --fetch-full-installer --full-installer-version 10.13.6
Downloading and installing 10.13.6 installer
Install failed with error: Update not found

I found a USB keyboard and mouse. Once I plugged that in it allowed me to advance and run the High Sierra installer that the “shift-option-command-r” downloaded. What I find strange is after the installer finished and rebooted with the “welcome to Mac” screen, it allowed me to use the bluetooth keyboard and mouse.

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