Windows 10 failed to boot after upgrade from Windows 7

I recently attempted to upgrade a Dell Latitude laptop from Windows 7 to Windows 10. I started with a clean Win7 installation with most of the updated device drivers from Dell. The upgrade went smoothly … until it rebooted and I got the following error:
xC1900101 - 0x20017 Installation failed during safe OS phase with an error during boot operation
The good news was the installer backed out the upgrade and I was able to use the laptop with Win7. Researching this error code provided lots of suggestions related to hardware like removing RAM, disabling wireless and Bluetooth and so on. These worked for some people but not all so I kept digging.
Then I remembered that one of the things I didn’t upgrade was the BIOS. It was running version A06 and the current version from Dell was A16. Once I figured out I had to do a two-step upgrade (going directly to A16 did not work), I reran the upgrade tool and it worked, no boot error.
As a side note I found out that if you upgrade by downloading the installer from the Internet (rather than an ISO) the install files are stored in “c:\windows\$Windows.~BT”. You can run setup from this folder to avoid downloading the files again.

Networking Windows 10 Dell