I am done.

Yes, you can.

You can even remove the old version of Windows before the upgrade (stored in folder Windows.old)

Free up drive space in Windows 10

If your PC is running low on storage, here are a few ways to free up some drive space.

Delete temporary files

These files used to help your apps load and run faster, but they're not being used anymore. To delete them:

Open the Start menu and select Settings > System > Storage.

Under Storage, select This PC > Temporary files.

Under Temporary files, select Delete temporary files > Yes, I'm sure.

Same here. I have upgraded 4 machines without a single problem.

Yup.

The C drive has shrunk 450MB at the end to make way for a new Windows 10 recovery partition.

Here is the Windows 10 450MB recovery partition.

The missing Windows Start Up Sound is back after applying the first cumulative update today.

Thanks, Microsoft!

If you can elaborate on what these unnecessary features are, maybe we can help.

You can turn off "Choose how updates are delivered". The default is ON.

Mine is the Intel HD Graphics 4400 and the driver was installed successfully during the upgrade to Windows 10. No issues at all.

After performing a clean install of Windows 10, I get activated immediately once my PC is online.

But then, I entered the Windows 10 product key during the clean install, which I extracted earlier after upgrading from Windows 8.1 to Windows 10.

You have skipped entering the Windows 10 product key during the clean install.

It is quite normal because not everyone knows how to extract the Windows 10 product key AFTER the upgrade.

Since yours is a legitimate clean install, you should wait for the activation.

Eventually you will be activated since Microsoft already knew your hardware ID during the upgrade process.

Don't worry.

Nope.

The extracted Windows 10 key after Windows 8.1 upgrade is a generic key.

Only the hardware ID established during the upgrade ties that generic key to your PC hardware.

You won't see it IMMEDIATELY. Wait a while, a day or two.

It is only him.

Like I said earlier, it is only you.

Anybody who tries to use a Windows 8.1 key for Windows 10 will face the same problem as you.

There is no problem at all with upgrading Windows 8.1 to Windows 10 if you do it the proper way.

In Windows 8.1, you click on the setup.exe in the downloaded Windows 10 folder to start the upgrade process.

You don't need to enter any keys during the upgrade process.

How dangerous is this piece of information?

Just the name "Danny".