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

Question

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"
  }
}

Solution 3

Go to Programs and Resources, use "Core" to filter and find Preview 3 installation ("Microsoft .NET Core 1.0.1 - SDK Preview 3 (x64).") and remove it.

NOTE: Run dotnet --version before and after remove this SDK. On my case results in 1.0.0-preview3-004056(before) and 1.0.0-preview2-1-003177(after).

I can't see side effects on vs2017 yet.

Solution 4

Take a look at this link: https://github.com/aspnet/Tooling/blob/master/known-issues-vs2017.md#known-issues-for-aspnet-core-support-in-visual-studio-2017

If you update the tooling for Visual Studio 2015 to the latest version, it should fix the issue. Note this is not the Visual Studio 2015 update, but the ASP.NET Core and tooling.

View more solutions

Comments

[Stephen Peterson]

I'm not sure what installing the latest ASP.NET Core 1.1 tooling would have to do with opening a ASP.NET Core 1.0 app in VS 2015 and not having it work with VS 2017 RC installed. I can see if you wanted to upgrade your existing ASP.NET Core 1.0 app to 1.1, in VS 2015, but installing VS 2017 RC should have nothing to do with how VS 2015 works, especially with .NET Core projects created in VS 2015

[dfmetro]

Worked for me thanks. @Luiz would have gotten the answer as he was first but his answer wasn't detailed

[bougiefever]

That is one way to fix it, however, you can add a global.json file to your solution (solution file, not added at the project level) specifying the core version to use { "projects" : [], "sdk":{ "version":"1.0.0-preview2-003121"}}

[thangchung]

Thank you. I was very confusion after upgraded to VS 2017 RC. But now it works.

[cel sharp]

Aditionally I had to run dotnet restore on each project, but after that everything worked as expected.

[Mathieu K.]

What is this new solution folder you speak of?

[MarioAraya]

I got two projects .NET core that failed after VS2017, but when create one "global.json" for each project, all works fine!! thanks

[Hussein Salman]

Same problem here also global.json exits

[Nisar]

It did not worked with "version": "1.0.0" but when i tried "version": "1.0.0-preview2-003131" it worked.... Thanks for saving lifes...

[resnyanskiy]

Important notice from @Nisar. There is also almost the same answer in official dotnet docs

[gosr]

@MathieuK., maybe you don't need to put this json file in any subfolder, at least I just had to put it in the root folder. Also, unloading and reloading the project afterwards did it for me.

[PabloCocko]

It's explained here blogs.msdn.microsoft.com/dotnet/2017/08/14/… , go to "Relationship to .NET Core 1.0 and 1.1 Apps" section