Unable to reinstall macOS High Sierra, with "Recovery server could not be contacted" message.

Yes, but the older Macs Boot ROMs cannot understand APFS, you need HFS+ & let the Intaller change it to APFS.

Yes, you may need to start with Lion, actually I think 10.11 for App Store usage.

Make a USB Installer...

Bottom line: You're stuck. The ability to reinstall macOS from Apple's Recovery servers is gone. There is no point in proceeding any further with it. The fat lady has sung; Elvis has left the building.

Options:

• Create a "bootable USB installer" on an eligible Mac, and boot from it to reinstall High Sierra on that one.
• Restore a Time Machine backup of that Mac created prior to having its internal storage fail.
• Restore a Time Machine backup of any other Mac running an operating system that Mac can run (High Sierra, probably). This will restore High Sierra, which more recent macOS versions don't do.
• Ask an Apple Store to reinstall macOS. Their ability to do that has been confirmed by at least one ASC participant.

Lastly:

• Attempt an extremely tortured workaround to extract the High Sierra installer from Apple's cdn servers. I have not done that, and it will take a long time for me to provide instructions if I can even find them and confirm that they actually work. For all practical purposes this method exists only in theory.

The third option of this solution worked for me. Good luck!

https://mrmacintosh.com/how-to-fix-the-recovery-server-could-not-be-contacted-error-high-sierra-recovery-is-still-online-but-broken/

John Galt wrote:

The ability to reinstall macOS from Apple's Recovery servers is gone.

Minor correction:

The ability to reinstall High Sierra (and earlier OS versions) from Apple's Recovery servers is gone.

Poking through my USB flash drives, looking for some extra ones to try building installers on, I found one with the El Capitan (10.11) on it. That one installs fine, so maybe from that I can build an installer for High Sierra (I could try the upgrade directly, but I do want to reconfigure the layout, so I want the ability to run a fresh install). Don't even remember why I had 10.11 on USB.

Oh, and by the way, I have bone through that EXACT SAME Apple Support document as well, and worked through it's steps. And I can definitely say the process FAILED multiple times. I've tried with different downloads, different flash drives, ALL have failed. So don't say I didn't read them.

Ah, sorry I did miss that.

As Create a bootable installer - Apple Support states,

"... To download a full installer, your Mac must be using macOS High Sierra or later, the latest version of macOS Sierra, or the latest version of OS X El Capitan."

The images are not corrupted. I can confirm those instructions work, exactly as described. Nothing else will work. Forget using a Linux machine or anything else that is not explicitly described in those instructions. They must be followed to the letter. It will work.

Apple's errors quite often have no real meaning, did you format the drive HFS+ or APFS?

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.

The solution posted by heycoach appears to resemble the tortured workaround I alluded to earlier. I just haven't been able to verify that exact procedure yet. If it makes sense to you, try it.

Asking an Apple Store to install High Sierra is also an idea worth pursuing. You might have to catch them on a good day.

I wouldn't give up on High Sierra quite yet. Even if I did, I'd pursue installing some Linux variant on that Mac before Windows. I only used Windows enough to learn I never want to use it again, and that was a very long time ago.

(Apple apparently didn't like that I chastised them for shoddy engineering. I'd expect nothing less)

I had downloaded the High Sierra image multiple times, on multiple machines (MacBook and a Linux laptop). I've tried their terminal command with "createinstallmedia", and trying to run it on the iMac still results in a bad/damaged image message. Perhaps the images on the Apple server are corrupted?

Well, this 27" iMac could make a very nice Fedora Linux machine.

I am using ****Catalina**** to download the images (downloading on Linux was to test if there was any difference in the quality of the images downloaded). Even though the instructions *claim* you could download through the AppStore, all it does is complain that my OS version is already newer. Well, DUH, I'm not trying to download it for the machine I'm on, I need it for a different machine. And if I manage to install 10.8 or 10.9 on the iMac, it can't manage to open the AppStore (probably because too much changed in the AppStore in the interim).

The browser downloaded image (downloaded through ***Safari***) and writtten to USB with the createinstallmedia command starts on the iMac, then says it's a corrupt/bad image. If the instructions tell me I can do an internet install, but any "supported" versions have been removed from the servers, then the instructions are no longer helpful. If it says I can get the installer from the app store, yet the app store says I can't get it, then the instructions are no longer helpful.