I upgraded one of my PC's from Windows 7 to Windows 10 last night using the automatic upgrade. After a few hours the PC was stuck on a black screen. The cursor was there and movable, but nothing else was up.
I restarted a few times and brought up the recovery manager. I started the PC in Safe Mode but still it would show the windows logo and then go to the black screen.
It turns out it was a videocard / monitor issue. I have multiple monitors through an Nvidia GTX card. My PC also has intel onboard graphics (which I had disabled under Win 7 since I didn't need it). It seems Win8 saw the onboard graphics and decided to use that as the main display(even though it had no monitors attached). The Nvidia (which was the previous main display) was used for secondary, hence the black screen with the cursor.
To fix it I simply plugged one of my monitors into the onboard video. And just like that, the login screen appeared. After logging in with my user/pass the system continued with the setup.
Long story short, if you have multiple monitors or video cards, attach a display to the onboard graphics when doing the upgrade and you can save yourself some headache.
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