The attribute "Include" in element <PackageReference> is unrecognized

Question

I created a Directory.Build.props file by right clicking the Solution on Solution Explorer, creating an XML file, and named it so. I then input this XML and tried building but was met with errors:

<Project>
    <PropertyGroup>
        <Version>1.2.3</Version>
        <Authors>John Doe</Authors>
        <PackageReference Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="6.0.0">
            <PrivateAssets>all</PrivateAssets>
            <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
        </PackageReference>
    </PropertyGroup>
</Project>

The errors say: The attribute "Include" in element <PackageReference> is unrecognized. and

Project "C:\redacted\Directory.Build.props" was not imported by "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\MSBuild\Current\Microsoft.Common.props" at (33,3), due to the file being invalid. ProjectName C:\Users\me\source\redacted\ProjectName\Directory.Build.props   33  

I am so confused here. The other articles said to locate the MSBuild and I know that its on my machine. The build was working just fine prior to me adding the XML too. Any guidance would be very appreciated. I am currently on Visual Studio 2022 by the way.

Answer 1

The PackageReference element needs to be in an ItemGroup - you've got it in a PropertyGroup . It should look like this:

<Project>
    <PropertyGroup>
        <Version>1.2.3</Version>
        <Authors>John Doe</Authors>
    </PropertyGroup>

    <ItemGroup>
        <PackageReference Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="6.0.0">
            <PrivateAssets>all</PrivateAssets>
            <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
        </PackageReference>
    </ItemGroup>
</Project>

Answer 2

I had the same kind of problem one time and I found out it was caused by '\xef\xbb\xbf#' which is a 'Unicode BOM(Byte Order Mark)' and consists of invisible characters added by certain text editors like Notepad++, for instance. The BOM often functions as a magic number used to pass along information to the program reading the file, such as the Unicode character encoding or endianess but it's presence can interfere with software that does not expect it. The way I found it by fluke was I had my csproj file on github and when I clicked 'edit', the BOM stuck out like a red dot. I simply backspaced on it and then everything went well.

Answer 3

I came accross the same kind of problem, for me it was due to invalid XML structure:

<ItemGroup>
    <PackageReference Include="Microsoft.VisualStudio.Threading.Analyzers" Version="17.2.32">
    <PackageReference Include="Microsoft.CodeAnalysis.BannedApiAnalyzers" Version="3.3.3">
    </PackageReference>
</ItemGroup>

As you can see, the first PackageReference tag was not closed, leading to the exact same error The attribute "Include" in element <PackageReference> is unrecognized. on the second PackageReference tag.

Valid XML structure:

<ItemGroup>
    <PackageReference Include="Microsoft.VisualStudio.Threading.Analyzers" Version="17.2.32"/>
    <PackageReference Include="Microsoft.CodeAnalysis.BannedApiAnalyzers" Version="3.3.3"/>
</ItemGroup>

I hope that can help somebody else !