How to upgrade 1511 from Home to Pro?

I'm not having any luck figuring out how to upgrade from Home to Pro with an existing key.  My system has been running Home and is currently running version 1511.  I've decided to go ahead and use an existing key to upgrade to Pro.  I did a clean install, expecting to be asked to specify a version and provide a key during install, but was never asked for either.  The installer simply formatted the hard drive and installed Home and activated it, with no input from me after the install started other than agree to the terms and tell it my language.

OK, no problem I thought, I'll just go to the Activation setting and give it the new key from there.  However, if I tell it I want to change the key it comes back and says the key I'm giving it can only activate Pro and I'm running Home.  If I go the Store route and tell it I already have a Pro key, it gives me the same message - it tells me my key is for Pro but I'm running Home.  Nowhere along the way does it offer to take my key and give me the upgrade, rather it implies that I must somehow magically upgrade it myself before changing the key.  And that would be fine if I could figure out how to do that.

Anyone know how to force an install of Pro when the installer automatically installs Home with no option given to change it?

I'm not having any luck figuring out how to upgrade from Home to Pro with an existing key.  My system has been running Home and is currently running version 1511.  I've decided to go ahead and use an existing key to upgrade to Pro.  I did a clean install, expecting to be asked to specify a version and provide a key during install, but was never asked for either.  The installer simply formatted the hard drive and installed Home and activated it, with no input from me after the install started other than agree to the terms and tell it my language.

OK, no problem I thought, I'll just go to the Activation setting and give it the new key from there.  However, if I tell it I want to change the key it comes back and says the key I'm giving it can only activate Pro and I'm running Home.  If I go the Store route and tell it I already have a Pro key, it gives me the same message - it tells me my key is for Pro but I'm running Home.  Nowhere along the way does it offer to take my key and give me the upgrade, rather it implies that I must somehow magically upgrade it myself before changing the key.  And that would be fine if I could figure out how to do that.

Anyone know how to force an install of Pro when the installer automatically installs Home with no option given to change it?

Did you correctly create the media using only Media Creation Tool and then boot it as a UEFI device if offered, delete all partitions down to Unallocated Space (or it is not clean), then click Next to let it auto-create and format the needed partitions - which makes it foolproof? 

If so it should have given you a menu to choose Pro version unless it's a WIndows 8 PC with an embedded Home Product Key which will always force install of Home. 

There should have been no key inserted during install unless you have a retail Product Key that has never converted to a Digital License in Activation Settings.  If any key is inserted besides the default Version Key then it will fail.

To advance to from Home to Pro now, insert the default Pro Version key from here:  http://winaero.com/blog/generic-key-to-install-windows-10-rtm/ to change to Pro version.  But after Version 1803 if you don't yet have a Pro Digital License it will fail, so to workaround this go offline by choosing Airplane Mode in Action Center at right end of Task Bar.  It will then allow inserting the Pro generic version key to Upgrade to Pro, after which it should activate with a valid Pro Product Key in Activation Settings. 

If not contact Customer Service to validate the key here:  https://support.microsoft.com/en-us/help/4051701/global-customer-service-phone-numbers

Did you correctly create the media using only Media Creation Tool and then boot it as a UEFI device if offered, delete all partitions down to Unallocated Space (or it is not clean), then click Next to let it auto-create and format the needed partitions - which makes it foolproof? 

If so it should have given you a menu to choose Pro version unless it's a WIndows 8 PC with an embedded Home Product Key which will always force install of Home. 

There should have been no key inserted during install unless you have a retail Product Key that has never converted to a Digital License in Activation Settings.  If any key is inserted besides the default Version Key then it will fail.

To advance to from Home to Pro now, insert the default Pro Version key from here:  http://winaero.com/blog/generic-key-to-install-windows-10-rtm/ to change to Pro version.  But after Version 1803 if you don't yet have a Pro Digital License it will fail, so to workaround this go offline by choosing Airplane Mode in Action Center at right end of Task Bar.  It will then allow inserting the Pro generic version key to Upgrade to Pro, after which it should activate with a valid Pro Product Key in Activation Settings. 

If not contact Customer Service to validate the key here:  https://support.microsoft.com/en-us/help/4051701/global-customer-service-phone-numbers

I have used this technique exactly as you described more times than I can count now and it worked "as advertised" every single time on a variety of different brands of computers.  I do not see why these folks are having such a hard time doing this simple procedure when you have described (over & over again, in great detail) precisely how it is to be performed.  It's basically just "put in the ingredients, turn the crank and out pops Windows 10 Professional".  I wonder if people are actually reading your instructions?

I'm not having any luck figuring out how to upgrade from Home to Pro with an existing key.  My system has been running Home and is currently running version 1511.  I've decided to go ahead and use an existing key to upgrade to Pro.  I did a clean install, expecting to be asked to specify a version and provide a key during install, but was never asked for either.  The installer simply formatted the hard drive and installed Home and activated it, with no input from me after the install started other than agree to the terms and tell it my language.

OK, no problem I thought, I'll just go to the Activation setting and give it the new key from there.  However, if I tell it I want to change the key it comes back and says the key I'm giving it can only activate Pro and I'm running Home.  If I go the Store route and tell it I already have a Pro key, it gives me the same message - it tells me my key is for Pro but I'm running Home.  Nowhere along the way does it offer to take my key and give me the upgrade, rather it implies that I must somehow magically upgrade it myself before changing the key.  And that would be fine if I could figure out how to do that.

Anyone know how to force an install of Pro when the installer automatically installs Home with no option given to change it?