Tried this trick, but not working.
Then I tried Windows Media Creation Tool. Problem is, after it ends the download, the window disappear and I can't install!
I tried the wuaucllt.exe /updatenow command and all it did was remove the "reserve windows" icon from my taskbar so now I'm not even sure the update will still download.
How do you bring up the command prompt I used earlier today and now I can't remember how to bring it up again.
I had success getting it to download and prepare to install but then I got an error message that the install had failed. My computer is fully compatible so I don't know what happened. Now I can't get it to work again. I guess Big Brother foiled my plan. If I had known that reserving a copy was not going to get me the OS on the 29th I would have done something different. Auspicious start.
Locate the registry key: [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\OSUpgrade]
It should exist, but if not, create it.
Create a new DWORD (32-bit) Value with Name = "AllowOSUpgrade” (without the quotes), and set the Value = 0x00000001.
Once the registry key is modified, close and reopen the desktop Control Panel, go to Windows Update and check for updates. You should now be able to click the Get Started button to upgrade to Windows 10. Note: Windows 8.1 users must go to the desktop Control Panel, and not the modern Windows Update UI.
Windows Update Installation Failure 80240020 - Microsoft Community
Official Microsoft solution:
Turns out there was nothing wrong for many (most?) of us, Microsoft just decided to give us a really ****ty error message. We were just lower on the install priority list.