Unable to re-install OSX Yosemite after erasing hard drive

You will require that Mac Pro's two original grey discs. A knowledgeable buyer will want them, and you don't want to sell your Mac to anyone other than a knowledgeable buyer. A neophyte will only get frustrated, and you will probably bear the brunt of that anger.

A knowledgeable buyer will also know what to do if you are unable to provide those discs. Presumably he'll already have had some other way to install OS X, perhaps from a previously created "bootable USB installer", or perhaps installing an operating system won't be important. For example that Mac Pro will make a fine Linux computer (and that's what I'd do with it). But the bottom line is that you must revert that Mac's original factory settings before selling it.

If for whatever reason you can't do that, sell it in its present condition, but be forthcoming about the fact you are unable to comply with Apple's instructions for selling a Mac: What to do before you sell, give away, trade in, or recycle your Mac - Apple Support. Those instructions are not optional.

Yes. You may want to provide them the following links for downloading various versions of macOS installers and also instructions for creating a bootable macOS USB installer (highly recommended so that they don't need to use CDs to start the process over if something goes wrong).

How to download and install macOS - Apple Support

Create a bootable installer for macOS - Apple Support

Both Yosemite and El Capitan from outside of the Apple App Store so any computer running any OS (even Windows) can download the DMG installer, then just transfer the DMG to this older laptop so the real installer can be extracted into the Applications folder from the DMG (need to run the .pkg file within the mounted DMG). The Apple article I linked provides these instructions of a person carefully reads the entire article.

Option-⌘-R

Upgrade to the latest macOS compatible with your Mac.

Look at top of screen for Utilities menu...

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

Run Disk First Aid on all items in the left panel, from top down.

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.

More details...

Like many others, I ran into the dreaded “The recovery server could not be contacted” message when trying to do a restore of Mac OS High Sierra for a 2010 13 inch MBP that I was selling (yes I know it’s worth almost nothing, but someone wanted to buy it from me)…

How to recover a Deleted Hard Drive durin… - Apple Community

If all else fails...

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

High Sierra “The Recovery Server Could No… - Apple Community

Use http:// instead of https://

https://www.youtube.com/watch?v=ouNQS36dIBw&t=95s

The formula for caos: APFS+macOS High+EFI… - Apple Community

How to recover a Deleted Hard Drive durin… - Apple Community

ssquared30 wrote:

I've followed all the instructions on this page:

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

I would try Fix #3 in that article, but make sure you are booted into Recovery Mode by using Command + Option + R. Since it is a 2008 model, there is no Internet Recovery Mode, so this option should give you access to the Yosemite installer on the internal drive, but should avoid needing to authenticate with an AppleID. Theoretically those instructions should work for other versions of macOS, but hard to say since this is a 2008 model that did not have Internet Recovery Mode.

Unfortunately Apple has made a mess of trying to reinstall macOS on these older Macs. So if you cannot get this working, then @John Galt's suggestion is the only alternative which will work. Better yet, get an OS X 10.6 Snow Leopard Upgrade DVD (one with the cat pictured on the disc...not the gray disc). Once you have OS X 10.6 Snow Leopard installed, then you can download Yosemite or El Capitan (you will need to download them using another computer since Snow Leopard won't be able to access the Apple website) so you can upgrade the system to it.

If you just want to have any OS installed on the system in order to show it is functional, then you can install Linux Mint on it. It would make the system much more usable as it would have an up to date non-Apple OS which has access to the popular web browsers (Firefox, Chrome, Vivaldi, etc.), plus lots of free open source software within the Linux Mint software repository. If you only install Linux Mint to the erased "Macintosh HD" volume without touching the local recovery mode partition, then you will still have access to the old Yosemite installer on the hidden recovery partition.

Yes. If those discs are grey, they will be a valuable selling point certain to attract buyers who know what they're looking for. I don't pretend to know what that Mac Pro's present market value happens to be, but it's certain to be a nice find.

Try setting the Date & Time, if it's off by 30 seconds that can cause a siteto refuse connection...

https://bensmann.no/changing-system-date-from-terminal-os-x-recovery/