Hello paulh333,

We have a great support article that might help with this. Please take a look at it here: If an error occurred while updating or installing macOS - Apple Support. Follow this guidance:

"Check your internet connection

Even if you're not installing macOS from the internet, the installer needs the internet to get firmware and other information specific to your Mac. Make sure that your Mac has a working and stable internet connection.

Install in safe mode

Install while your Mac is started up in safe mode. To start up in safe mode, determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:

Apple silicon

Intel processor

Install after repairing your disk

Use Disk Utility to repair your startup disk. Then try updating or installing macOS again.

Install from macOS Recovery

Install while your Mac is started up from macOS Recovery. This gives you the latest version of the macOS currently or most recently installed. To start up from macOS Recovery, follow the appropriate steps:

Apple silicon

Turn on your Mac and continue to press and hold the power button until you see the startup options window. Click the gear icon labeled Options, then click Continue.

Intel processor

Turn on your Mac and immediately press and hold Command (⌘)-R until you see an Apple logo or other image.

If you're asked to select a user you know the password for, select the user, click Next, then enter their administrator password. When you see the utilities window in macOS Recovery, select Reinstall macOS, then click Continue and follow the onscreen instructions. Learn more about using macOS Recovery to reinstall.

Install after erasing your Mac

If no other solutions work, erase your Mac, then reinstall macOS or restore from a backup.

If the issue persists or you need help, please contact Apple Support."

We hope this helps. Let us know if we can assist with anything else at all. Take care.