BC30560：名称空间'System.Runtime.CompilerServices'中的'ExtensionAttribute'不明确 [英] BC30560: 'ExtensionAttribute' is ambiguous in the namespace 'System.Runtime.CompilerServices'

问题描述

我有asp.net项目（在.net 2.0中），并将项目转换为.net 4.0。
成功构建项目后，我在浏览器上启动了网站，并引发如下错误：

I have asp.net project (in .net 2.0) and I converted project to .net 4.0. After I built the project successfully, I launched the website on browser, it throws error as following:

编译错误

Compilation Error

描述：在为该请求提供服务所需的资源
的编译过程中发生错误。请查看以下特定的
错误详细信息，并适当地修改您的源代码。

Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

编译器错误消息：BC30560：在
命名空间 System.Runtime.CompilerServices中， ExtensionAttribute不明确。

Compiler Error Message: BC30560: 'ExtensionAttribute' is ambiguous in the namespace 'System.Runtime.CompilerServices'.

源错误：

[无相关源代码行]

[No relevant source lines]

源文件：InternalXmlHelper。 vb行：9

Source File: InternalXmlHelper.vb Line: 9

........

推荐答案

.NET 2中使用扩展方法（用于LINQ等）的常见技巧。使用C＃3（或更高版本）的编译器是在正确的名称空间中定义自己的ExtensionAttribute。

A common trick to use extension methods (for LINQ etc) in .NET 2 with the C# 3 (or above) compiler was to define your own ExtensionAttribute in the right namespace.

现在，您已升级到更高版本的.NET，您需要删除此现在多余的额外属性。查找在代码中定义的位置并删除它。还要检查诸如LINQBridge之类的外部库-您将不再需要它。

Now that you have upgraded to a later version of .NET you need to remove this now-redundant extra attribute. Find where it is defined in your code and expunge it. Also check for external libraries like LINQBridge - you won't need this any more.

找到它的一种方法是使用对象浏览器并搜索ExtensionAttribute。

One way to find it would be to use the object browser and search for ExtensionAttribute.

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