Question: The information about ASP.NET Core MVC 1.0 (aka MVC 6) is a little light from Microsoft, so there's a few questions still unanswered. One question I have is in regards to backwards compatibility and upgradability. It's known that WebForms is not part of ASP.NET Core 1.0.

What is unclear is whether ASP.NET Core MVC 1.0 (aka MVC 6) will run on both ASP.NET 4.x AND ASP.NET Core 1.0? Or is ASP.NET Core MVC 1.0 only compatible with ASP.NET Core 1.0?

When attempting to upgrade the ASP.NET MVC nuget package from MVC 5 to MVC 6 (final RC1 at this time) the following error is given in Visual Studio:

> 
> Unable to find a version of 'Microsoft.AspNet.Razor' that is compatible with 'Microsoft.AspNet.Razor.Runtime 4.0.0-rc1-final constraint: Microsoft.AspNet.Razor (≥ 4.0.0-rc1-final)', 'Microsoft.AspNet.WebPages 3.2.3 constraint: Microsoft.AspNet.Razor (≥ 3.2.3 && < 3.3.0)'.
> 
> 
> 

It's unclear if this is a versioning issue with the RC, or if ASP.NET Core MVC (aka MVC 6) will not be supported on ASP.NET 4.6?

Basically, does/will ASP.NET Core MVC 1.0 (aka MVC 6) support running on ASP.NET 4.6?

Answer: 
No it won't.

MVC 6/MVC Core 1.0 is aimed at, and only compatible with ASP.NET Core.
You are going to have to do a manual upgrade / conversion of your application. 

you basically have three options, 
1: convert everything in one shot.
2: convert as your go and have your site be actually two sites that work together until you finish the conversion
3: stick with what you have and do not upgrade. 

many reasons for choosing each option...