Bootcamp fails to authorize licence key during installation. How do I remove residual items from previous bootcamp and parallels installation?

Thanks, I will keep that in mind.

1. Was Windows 7 on the old Mac a Bootcamp/Windows installation which was also used as a Virtual Machine using Parallels?

Yes.

2. If you have a new license of W8.1, is it an upgrade or a full installation?

Full installation, not an upgrade.

3. Do you have files on the W7 installation that you need to transfer to the W8.1 installation?

Eventually, yes, but I am prepared to manually transfer all that I need, once I have a clean install of W8.1.

4. Are there applications on the old W7 installation that you do not want to re-install?

Yes.

5. If the W7 BC/Windows installation was transferred to a newer 2015 MBP, there are hardware differences, including W7 drivers. Was the W7 installation 'generalized' (SysPrep'ed) and then moved?

I did not transfer the W7 partition, it failed to SysPrep. I left it undisturbed and just followed the Apple instructions for transfer of my old mac to the new mac via thunderbolt.

6. What is the failure in BCA on the new 2015 MBP? BCA does not look 'inside' an existing BC/Windows installation and look for files. It looks at the current Mac environment to determine Windows existence (NVRAM information, partitioning layout, etc.).

BCA does whatever it does to the point where I am required to enter the authorization key. I enter it and can get no further and have to stop the installation and restore the partition for the mac. I expect BCA is looking through the mac files and finding that there is supposed to be an existing W7 installation.

Maybe I just have to delete some plists? I am no expert as you can tell.

Thanks for your help.

When the Windows Setup fails to accept the key in the window, I get the message within the window that says "The product key didn't work. Please check it and try again". Not a black screen.

However, I did make the iso file with a new USB3 flash drive, so if it has to be USB2, it is going to fail, right?

Hopefully that is the source of the fail at this point. I will reformat an old USB2 and make a new iso and see how it goes.

Thanks.

When the Windows Setup fails to accept the key in the window, I get the message within the window that says "The product key didn't work. Please check it and try again". Not a black screen.

However, I did make the iso file with a new USB3 flash drive, so if it has to be USB2, it is going to fail, right?

Hopefully that is the source of the fail at this point. I will reformat an old USB2 and make a new iso and see how it goes.

Thanks.

Win8.1 Download iso Checksum is fine. Created install disc on USB2 stick. Got exactly the same fail point.

I think there are likely to be residual files carried over from the W7 bootcamp of the old MB pro.

I will try the Bootcamp Forum.

Thanks

I reset as instructed and still get the same fail point.

Any further ideas?

No I do not.

How do I get one?

I downloaded a VL iso from the internet (I am a home user with no IT department).

It installed via Bootcamp Assistant and runs OK, but no product key was supplied with this iso and the key that I purchased previously does not work, so I can not activate it.

What do you suggest? I think I might claim a refund for my purchase and try a different supplier, but maybe I should install the purchased copy again as far as it will go and phone Microsoft to get them to authorize the key.

The VL version that installed does not come with a product key, so I guess it is illegal.

The version that I bought came with a product key and I tried to get the key entered many times into that version without dashes and with several install attempts.