error in csproj - duplicate item

Question

I have error from visual studio 2010:

Error 1 The item "CrossDomainService.svc.cs" was specified more than once in the "Sources" parameter. Duplicate items are not supported by the "Sources" parameter. WcfServiceDomain

and from msbuild

C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.CSharp.targets(160,9) : error MSB3105: The item "CrossDomainService.svc.cs" was specified more than o nce in the "Sources" parameter. Duplicate items are not supported by the "Sources" parameter. [C:\inetpub\Wwwroot\axaptaWcfConnection\WcfServiceDomain\WcfSer viceDomain.csproj]

My file is csproj:

    <?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
  <PropertyGroup>
    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
    <ProductVersion>
    </ProductVersion>
    <SchemaVersion>2.0</SchemaVersion>
    <ProjectGuid>{8D40933A-E036-4CD0-9003-314A692724D5}</ProjectGuid>
    <ProjectTypeGuids>{349c5851-65df-11da-9384-00065b846f21};{fae04ec0-301f-11d3-bf4b-00c04f79efbc}</ProjectTypeGuids>
    <OutputType>Library</OutputType>
    <AppDesignerFolder>Properties</AppDesignerFolder>
    <RootNamespace>WcfServiceDomain</RootNamespace>
    <AssemblyName>WcfServiceDomain</AssemblyName>
    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
    <TargetFrameworkProfile />
    <FileUpgradeFlags>
    </FileUpgradeFlags>
    <UpgradeBackupLocation>
    </UpgradeBackupLocation>
    <OldToolsVersion>4.0</OldToolsVersion>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
    <DebugSymbols>true</DebugSymbols>
    <DebugType>full</DebugType>
    <Optimize>false</Optimize>
    <OutputPath>bin\</OutputPath>
    <DefineConstants>DEBUG;TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
    <PlatformTarget>x86</PlatformTarget>
  </PropertyGroup>
  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
    <DebugType>pdbonly</DebugType>
    <Optimize>true</Optimize>
    <OutputPath>bin\</OutputPath>
    <DefineConstants>TRACE</DefineConstants>
    <ErrorReport>prompt</ErrorReport>
    <WarningLevel>4</WarningLevel>
  </PropertyGroup>
  <ItemGroup>
    <Reference Include="System.Web.ApplicationServices" />
    <Reference Include="System.Web.DynamicData" />
    <Reference Include="System.Web.Entity" />
    <Reference Include="System.Configuration" />
    <Reference Include="System.Drawing" />
    <Reference Include="System.EnterpriseServices" />
    <Reference Include="System.Runtime.Serialization" />
    <Reference Include="System.ServiceModel" />
    <Reference Include="System.ServiceModel.Web" />
    <Reference Include="System.Web.Services" />
  </ItemGroup>
  <ItemGroup>
    <Content Include="ClientAccessPolicy.xml" />
    <Content Include="CrossDomainService.svc" />
    <Content Include="Service1.svc" />
    <Content Include="Web.config">
      <SubType>Designer</SubType>
    </Content>
    <Content Include="Web.Debug.config">
      <DependentUpon>Web.config</DependentUpon>
    </Content>
    <Content Include="Web.Release.config">
      <DependentUpon>Web.config</DependentUpon>
    </Content>
  </ItemGroup>
  <ItemGroup>
    <Compile Include="CrossDomainService.svc.cs">
      <DependentUpon>CrossDomainService.svc</DependentUpon>
    </Compile>
    <Compile Include="ICrossDomainService.cs" />
    <Compile Include="Service1.svc.cs">
      <DependentUpon>Service1.svc</DependentUpon>
    </Compile>
    <Compile Include="IService1.cs" />
    <Compile Include="Properties\AssemblyInfo.cs" />
  </ItemGroup>
  <ProjectExtensions>
    <VisualStudio>
      <FlavorProperties GUID="{349c5851-65df-11da-9384-00065b846f21}">
        <WebProjectProperties>
          <UseIIS>False</UseIIS>
          <AutoAssignPort>True</AutoAssignPort>
          <DevelopmentServerPort>51421</DevelopmentServerPort>
          <DevelopmentServerVPath>/</DevelopmentServerVPath>
          <IISUrl>
          </IISUrl>
          <NTLMAuthentication>False</NTLMAuthentication>
          <UseCustomServer>False</UseCustomServer>
          <CustomServerUrl>
          </CustomServerUrl>
          <SaveServerSettingsInUserFile>False</SaveServerSettingsInUserFile>
        </WebProjectProperties>
      </FlavorProperties>
    </VisualStudio>
  </ProjectExtensions>
  <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v10.0\WebApplications\Microsoft.WebApplication.targets" />
</Project>

I not see any duplicate :/ Any idea from this error ??

Answer 1

I was facing the same problem in my solution with the same error for one of the source file,

I fixed it out as follows,

1. Check for the file name for which the error is given.

2. Find out in which project the file is included.

3. Open the .csproj file for that particular project (This file can be found in the directory where solution is placed).

4. Search for the file name for which the error is thrown in the .csproj file.

5. You will find two entries of the line such as

 <Compile Include="duplicate.aspx.cs">
      <SubType>ASPXCodeBehind</SubType>
      <DependentUpon>Duplicate.aspx</DependentUpon>
    </Compile>


 <Compile Include="duplicate.aspx.cs">
      <SubType>ASPXCodeBehind</SubType>
      <DependentUpon>Duplicate.aspx</DependentUpon>
    </Compile>

1. Delete any one line from one of them.

2. Save the changes.

3. Reload the project your error must have gone.