所有Visual Studio 2013构建现在都失败了

Question

Every single project I open in Visual Studio 2013 is now all of a sudden giving me the following error:

EverySingleProject.csproj : error : The default XML namespace of the project must be the MSBuild XML namespace. If the project is authored in the MSBuild 2003 format, please add xmlns="http://schemas.microsoft.com/developer/msbuild/2003" to the element. If the project has been authored in the old 1.0 or 1.2 format, please convert it to MSBuild 2003 format. C:\\Program Files (x86)\\MSBuild\\12.0\\bin\\Microsoft.Common.CurrentVersion.targets

This is in the file:

Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003"

Why is this failing?

Answer 1

You also get this error if you try and open a VS 2017 RC 'simplified' .NET Core csproj file in an earlier version of Visual Studio.

These new project files look like this:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp1.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.NETCore.App" Version="1.0.1" />
  </ItemGroup>
</Project>

(From: https://blogs.msdn.microsoft.com/dotnet/2016/12/12/updating-visual-studio-2017-rc-net-core-tooling-improvements/ )

You'll need to use a recent version of VS 2017 to open them.

Answer 2

I've had this like 2 days ago.

This saved me.

Hope this helps.

EDIT:

Fortunately the solution is simple:

1. In Windows Explorer navigate to the project
2. Right Click on the .cproj file, select Properties, and un-check the "Read Only" checkbox
3. Open up the .cproj file in Notepad
4. On line 2 change xmlns="http://schemas.microsoft.com/developer/msbuild/2008" to xmlns="http://schemas.microsoft.com/developer/msbuild/2003" (notice this only difference is we changed 2008 to 2003)
5. Save your changes
6. In Visual Studio right click on the (currently unavailable) project and select "Reload Project"
7. The project will now load normally and you can get on with your life

Answer 3

Turns out one of my files in the MSBuild folder got corrupted. This file: Microsoft.Common.CurrentVersion.targets

And another one of the files needed had vanished into the aether. This file: Microsoft.CSharp.CurrentVersion.targets

Neither of which were replaced, or fixed, during a repair and then a complete reinstall of Visual Studio.

I ended up copying the files across from another installation and now everything is back to normal.

Answer 4

Fixed it by adding:

<Project Sdk="Microsoft.NET.Sdk" ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">

in the .csproj file.

Answer 5

I had this as well. The project was probably (undocumented!) a VS 2017 project and I was using VS 2013.

What I did was:

1. Create a new VS 2013 web application project,
2. Copy and paste all the rest of the original project files into the new project folder,
3. Open the new project and include all the necessary original project files,
4. Mess about with references, etc for a while until all the compile errors disappear,
5. Run, test, tweak.

Really not ideal, but it was the quickest solution for a small demo project. Not sure how you'd go with a large solution. Maybe someone will build a converter sometime. Maybe Microsoft could do that. [Chuckles to self.]

Answer 6

删除相应的* .csproj.user文件有助于解决相同的症状。