If you've downloaded/installed the free upgrade Windows 10, make sure you check to see if it's activated.
It seems a lot of folk are unaware that this isn't always being done automatically. There are also reports that in a lot of instances, when you click to activate, the process isn't working, returning the Error code: 0xC004F034.
As this happened to yours truly, I did a quick search and discovered that the solution was rather simple. Instead of just clicking the 'Activate' button
once (which displays the error message each time), you have to continually/rapidly click on the button and it will eventually accept it. It took me around 10 clicks to get the activation acknowledgement, others have reported it can take 20 or 30 clicks.