Trying to clean install OS onto MBP - problems! Help please

[karansaraf]

I have a 2015 MBP which had High Sierra installed on it. I bought a new one and now sold this 2015 MBP on ebay so have been trying to get it ready to send.

I've booted up into disk utility, and erased my drive successfully.

I then exited disk utility to reinstall High Sierra from a bootable USB I created years ago when I did a clean install. Unfortunately it says it can't do this because the install location is damaged. So I reboot and try to install via Apple's download and install process. It goes through a few steps from the OS Utilities page and wants to install OS X Catalina (I guess this must have been the OS that came with the computer when I bought it). However, it then asks me to choose the disk I want to install it on, but nothing is present for me to choose!

Now I'm stuck. What do I do from here?

 

[Fishrrman]

"I then exited disk utility to reinstall High Sierra from a bootable USB I created years ago when I did a clean install."

I'll bet the "years ago" is your problem.
That's because the certificates for the old installers were permitted to expire, and now the installer won't run because of that.

But... there's a workaround (at least it works for some folks).
That is... SET THE INTERNAL CLOCK back to around Jan. 2018 or so.

Since you already erased the internal drive, I think you need to do it this way:
1. Boot from the USB installer
2. DO NOT attempt to install yet -- QUIT the OS installer
3. Open terminal
4. Enter this command:
date 010112002019
5. Close terminal and try the OS installer now.

Any better?

I suggest you WRITE DOWN ON PAPER the terminal command above.
Or print this out.

Let us know if this works.

 

[karansaraf]

So I managed to find a workaround, which was to partition the HD as I hadn't done that. This allowed me to install OS X. I've now updated (not clean installed) to Mojave and am creating a bootable drive for Big Sur. I'll follow the original process again to erase the disk and then install Big Sur, giving me a clean install.

Thanks!