Opening Visual Studio 2017 projects in Visual Studio 2015

Question

I've moved on to Visual Studio 2017 RC, but we still have people working on Visual Studio 2015. Currently when I create a project on 2017, it won't work on 2015. When the project is opened on VS2015 I keep getting the yellow triangles saying that there's a problem. And it won't build.

The error message associated with the yellow triangles is that it can't find those files. I am thinking that the issue is because of the new .csproj file that VS2017 uses instead of the project.json file that .net core has been using until now.

I thought that the projects created on VS2017 were backwards compatible with 2015. I guess they are not. Does anyone know if there's any way to create a project that can be worked on both VS2015 and VS2017? Thanks!

Solution

The new csproj-based projects for .NET Core aren't supported in Visual Studio 2015. There's a discussion about it here, but the gist of it is:

Rich Lander [MSFT]

We are working to get the new .NET Core msbuild-based tools finished
and at RTM quality as quickly as possible. They will be supported in
Visual Studio 2017+ and will be shipped as RTM next year. The changes
are significant, including to Visual Studio components, making it
very challenging for us to support them in Visual Studio 2015.

Comments

[Louis]

You could probably edit the csproj and/or the .sln based on one that was created in VS2015

[jmoerdyk]

Usually to maintain that kind of compatibility, you have to create the project/solution in the older version of VS.

[Zorthgo]

Well the problem here is that VS2015 can't find the libraries. Those yellow triangles are because the files don't exist (at least that's what VS2015 thinks). I am almost sure that the problem is caused because of the new .csproj file that VS2017 uses instead of the project.json file.

[Zorthgo]

Hi Brad, thanks for the info. I guess we'll have to decide to all move to 2017 or we all stay with 2015. I really appreciate the help, thanks! :D

[Admin]

No problem! It's a bit of a drag that the new tools break compatibility, but I imagine going back to msbuild is a huge change.

[ProfK]

Well, I think for all the RC users of VS2017, for which you should only be grateful, the ability to fall back on VS2015 when something suddenly doesn't work in VS2017 is an extremely high priority. Some sort of project file conversion extension for 2015 cannot be that hard to produce fairly quickly.

[ProfK]

And, @BradMelanson, I based on what I've seen in upgrades from 2017RC 2 to RC 4, I would wait well beyond March to move everything but experimental code to 2017. It is nowhere near ready to deal with all the complexities of debugging ASP.NET Core, and barely 2 weeks, focused on the whole of VS 2017, will not be enough to cover even that one problematic area.