DanielMcDill600 Said:
"I'm having the same issue with my 2015 MacBook pro, so far after two chats apple hasn't helped. do you have to have an adapter or do you know another way to fix it maybe?"
-------
Troubleshooting: "An error occurred while preparing the installation. Try running this application again."
Installing the macOS:
I. Use Ethernet:
If you are installing this using WiFi, then do so using Ethernet. If your Mac does not have Ethernet, this would be the adapter to use: Belkin USB-C to Gigabit Ethernet Adapter - Apple. If you get the same error, the model is likely just not compatible.
II. Two Methods to Perform: Restore or Reinstall Anew
A. Restoring the macOS:
Go Here: How to Reinstall macOS from macOS Recovery - Apple Support
Important: First, Back Up your Mac:
Prior to all of this, Create a Time Machine backup of your Mac, so that you can have something to restore your Mac from, should anything go wrong with the reinstall. Know to always create a backup of your Mac, prior to making any major changes to it (i.e. new install)
If no success...
B. Reinstall the macOS Anew:
See my User Tip: How to Reinstall the macOS Anew - No TMB Prior to Upgrade - User Tip. Format the hard drive with the applicable macOS, on step D.
In Depth:
Pretty much, it is a matter of:
- Erasing: and formatting your hard drive to APFS
- Installing: [the applicable macOS] via a USB Bootable Installer
- Restoring: info from a Time Machine Backup, using Migration Assistant