Background
I am upgrading a late 2012 27" iMac (Fusion drive) Replacing the mechanical part of the Fusion drive with a 2TB SSD. The device currently runs:
- High Sierra
- Win 10 via bootcamp.
Aim:
Fully configure the 2 TB SSD with MacOS with 10.15.5. and my current Bootcamp set up before I physically install it into the machine. I.e Ensure everything works and is migrated successfully before physically installing the SSD.
When the SSD is correctly configured I want to
- Install it in place of the mechanical hard drive.
- Set it up as the startup drive
- Erase 128GB blade.
My actions to this point are:
- 10.15.5 installed onto the SSD. The machine boots successfully when connected via USB. (Checked)
- The Bootcamp partition from the current Fusion drive running 10.13 has been cloned to an external USB device (preparatory to migration)
- Win10 ISO file downloaded.
- Win10 product key saved.
Issue
When I open Boot Camp Assistant to prepare the externally mounted SSD with a Bootcamp partition (prior to migration) I get the following error message at the first screen when I choose “Continue”
“Boot Camp Assistant has encountered a problem.
An internal error has occurred.”
Questions
- How do I resolve the error
- Is it possible to successfully achieve my aim in this use case. I have now found conflicting advice that it is not possible.
- If it is possible; are there any other preparatory actions I should take / next steps.
Any help is greatly appreciated.
Rs,
Sol