Good thread here, and some interesting solutions.
Another few things folks often miss while running DIY upgrades to W10 are: 1.) It's important to run the
Win10 COMPATIBILITY TEST; as misperforming apps and drivers are identified for you by this free Microsoft Tool. The
COMPATABILITY REPORT is both an included option with the Win10 Upgrade via download as well as a standalone tool here:
Upgrade Assistant: FAQ - Windows Help Many folks are aware of this option after Win10 has been out now for coming up on 1 year; but they often miss seeing and selecting the option while performing the Upgrade via download. Microsoft did a fine job offering this as a Standalone tool for those that either didn't know about the tool (usually for people doing their first ever Windows OS upgrade), or encountered a failed upgrade, and it can be run in Stand-alone mode to troubleshoot troublesome apps and drivers as stated.
2.) Home user upgraders also forget that if they are upgrading from earlier versions of Windows, such as Win7/8x, they often have older hardware. In the case of Win7 machines, Win7 was released in 2009, and if your computer came from the factory with a Win7 install, those computers are now turning 7 years old in 2016. Hard drives begin to fail after about 3 years of use; heavy duty use such as Graphics design, online Gaming, or other video intensive apps in laptops, sooner than that. If the Hard Drive has not been replaced during the life of a 7 year old machine, it's suspect, and can often be partially faulty but still operating. Drives in this category appear to be working until you attempt an OS upgrade, and then they become
"stressed" as the new OS often writes to damaged areas of the drive. In most cases upgraders can download the free
SEATOOLS diagnostic from Seagate.com and run
BOTH short and long tests on the drive prior to or after initial upgrade attempt. Should
SEATOOLS return any errors, the drive has failed and must be replaced!
It often is the source of the failing Win10 upgrade!
3.) Along the same line as item #2 above, the RAM should also be tested, even though this is more of a laptop failure than a desktop PC failure, due to the susceptibility of laptop drop damage; RAM can fail in an intermittent mode, producing symptoms of Memory Leaks, and even video failures during the upgrade process. Downloading the free
MEMTEST memory diagnostic can be run on the computer RAM for a minimum of 8 passes (
can take up to 24 hours or more on machines with 8-32GB RAM). If
MEMTEST returns any errors, then you have discovered 1 or more faulty RAM Sticks and they too must be replaced!
As noted in this thread by OP and others, software solutions can often fix problems from misbehaving or missing apps or drivers, but
NO SOFTWARE ON THE PLANET CAN FIX BROKEN HARDWARE!!! Most people, especially app users, and software designers often forget about the possibility of hardware failure. If you think about it, older computers are just like older cars, and if broken or failing parts are not diagnosed or replaced, catastrophic failure on upgrades are a quite common result.
If you attempt the solutions in the thread, and others you find on the web, and get no love including W10 clean installs, in-place upgrades, etc. It's worth running the COMPATABILITY TEST as well as the effort to test your primary hardware (RAM & Motherboard). This will often produce positive results, and I use it to fix "un-upgradeable machines which refuse to take Win10 but should specwise". Best of luck to you Win10 Upgraders! Hope this proves useful to you. 
<<<BIGBEARJEDI>>> 
