Re: M$ should be paying us!
"One could very well argue that if something as widely used on Windows 10 as Classic Shell
Well, how widely used is it? Last I heard it was discontinued.
is running then Windows 10 should be aware that instability could ensue and not do the upgrade.
I agree. Windows 10 (at least) has an internal black list that denies upgrades if there is some offending software installed. (e.g. some disk encryption s/w)
Since I'm not seeing the symptoms that Isces wrote about, I am inclined to believe that the update problems he faces are down to laptop models (drivers) or some esoteric configuration. I'm working with a sample set of perhaps a few thousand laptops from the usual providers so perhaps it's just me since my first reply has already garnered a lot of downvotes in short time? (="how dares he suggest the error is not Microsoft's")
One show stopper I found out the hard way was if the EFI partition (nearly) full. For example the HP Diagnostics are installed there and since the default partition size is a paltry 100MB, the diags eat up more than half of the space. The upgrade to newer Windows builds will just fail and the error message wasn't informative at all using Windows Update. Manual update gave a better error code which actually helped to figure things out and let the upgrade to continue.