How to reinstall macOS Sierra after it was wiped

Exactly which Mac model and year are you working with?

The version of macOS that you can install or upgrade to depends on having this information.

To reinstall macOS, start with the guidance found at this link:

How to reinstall macOS - Apple Support

You may have to boot your Mac in recovery mode to access Disk Utility and reformat the startup drive. Once that is done then reinstalling macOS would be the next step.

Installing the macOS version offered in recovery mode will likely be the easiest route. Once that is installed then you have options available to directly upgrading or creating a bootable USB installer that can upgrade your Mac.

If your Mac can run Sierra, then it can also run High Sierra and I would suggest you try at least to install that OS.

And if your Mac is compatible with newer macOS versions, then consider upgrading to any of those.

Try these workarounds and install High Sierra, if your Mac supports it. Reset PRAM before trying:

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

https://mrmacintosh.com/fixed-an-error-occurred-while-preparing-the-installation-macos-sierra-recovery-error/

Hi,

Start up in Recovery Mode( Option+Command+R key combination) could be your friend. you could reinstall with it, though you couldn't certification since it's quite old macOS you try to install on your Mac.