We wanted to let the businesses be very aware of the probable issues in the installation of the software. CIOs and IT administrators around the world are probably still thinking if they want to do the free upgrade or not, and it looks like they should wait for another few weeks. Otherwise, they'll be spending a lot of time troubleshooting, like us at Fudzilla.
After three attempts to update my main computer from Windows 7 to Windows 10 and a lot of reading, I managed to get it done. This Windows 7 installation survived many computer upgrades but it struggled to get the Windows 10 running. We probably don't have to explain why we skipped Windows 8 and 8.1 on this desktop machine, we had it on others but not on this one.  
None of the suggested things in the original article did work. It turns out that the antivirus was not causing problem. We continued reading and found that some users had to disconnect the secondary Hard Drive and all peripherals including the printer and webcam.