Visual Studio 2017 install breaks Visual Studio 2015 ASP.NET Core Projects

After installing Visual Studio 2017 Professional I can't build my ASP.NET Core in Visual Studio 2015 Professional anymore. I never opened this project in VS2017

I get

The following error occured attempting to run the project model server process (1.0.0-preview3-004056).

Unable to start the process. No executable found matching command dotnet-projectmodel-server

I then created a brand new ASP.NET Core project in Visual Studio 2015 and I get the exact same message when loading my project.

Additionally when I want to build the project I get

MSB1009: Project File does not exist.

The same problem does not occur with ASP.NET 5 projects so It's only limited to ASP.NET Core

Visual Studio 2017 7 March Update

Ifa global.json is added like in the answers below get an error message for any .net framework version used in the global.json and that exist in the C:\Program Files\dotnet\sdk\ folder

Error MSB4019 The imported project "C:\Program Files\dotnet\sdk\X.X.X\Microsoft\VisualStudio\v14.0\DotNet\Microsoft.DotNet.Props" was not found. Confirm that the path in the declaration is correct, and that the file exists on disk.

Also when closing Visual Studio and reopening it again I get the original error message

Solution 1:

@ClaudioNunes and @MegaTron have the correct answer. After reading that answer, I realized my .NET Core solution did not have a global.json file. I added a new solution folder and added a global.json file. Since none of my projects are nested in sub folders, I only had to remove "src" and "test" from the projects array:

{
  "projects": [],
  "sdk": {
    "version": "1.0.0-preview2-003131"
  }
}

The project now opens correctly in VS 2015 with VS 2017 RC installed.

Solution 2:

A possible workaround is to add a global.json to solution and specify the sdk version to be used as in

{
  "projects": [ "src", "test" ],
  "sdk": {
    "version": "1.0.0-preview2-003131"
  }
}