我在一个.csproj文件中有一个合并冲突，最终得到了一个构建目标的两个副本。

<编译包含=“SystemCodes\APSystemCodes.cs” />

在我消除了复制构建工作。

Visual Studio 2019这对我来说很有效:

关闭Visual Studio 删除隐藏的。vs文件夹 重新打开Visual Studio并重新构建解决方案。

在我的网页里。配置文件更改此

<?xml version="1.0" encoding="utf-8"?>

这个

<?xml version="1.0"?>

修正了我的问题

对我来说，问题是我打开了两个Visual Studio窗口，我的项目在一个窗口中运行调试，而我试图在另一个窗口中构建它。

我不得不停止调试，然后它让我成功构建。

发生此问题的原因是您正在使用的特性不受项目所选.net版本的支持。

对我来说，原因是我被利用了??运算符检查空值并抛出异常。

奇怪的是，VS并没有在构建错误列表中告知问题的实际原因。

但是您可以在构建的Output日志中找到这些信息。

The Visual Studio IDE doesn't do any building behind the scenes, the Msbuild application does. The VS IDE essentially just constructs the project file that is used by Msbuild and quite often it makes mistakes if you leave it up to the IDE to figure things out on it's own. If you are getting the Metadata file '.dll' could not be found error it is likely due to the fact that the correct/expected assemblies are not being found. So perhaps Visual Studio might be creating a project file for a 4.5 framework app, and expecting 4,5 assemblies, while you are referencing 4.0 assemblies. So look at your Visual Studio settings for incompatibilities or go into the project file yourself, and manually fix it by specifying the correct path <Reference Include="C:\\correct path to assembly\\yourAssembly.dll" />.