NETSDK1022: Duplicate items were included
This article applies to: ✔️ .NET Core 2.1.100 SDK and later versions
Starting in Visual Studio 2017 / MSBuild version 15.3, the .NET SDK automatically includes items from the project directory by default. These items include Compile
and Content
targets. This behavior simplifies project files.
However, if you explicitly define any of these items in your project file, you're likely to get a build error similar to the following:
Duplicate 'Compile' items were included. The .NET SDK includes 'Compile' items from your project directory by default. You can either remove these items from your project file, or set the 'EnableDefaultCompileItems' property to 'false' if you want to explicitly include them in your project file.
Duplicate 'EmbeddedResource' items were included. The .NET SDK includes 'EmbeddedResource' items from your project directory by default. You can either remove these items from your project file, or set the 'EnableDefaultEmbeddedResourceItems' property to 'false' if you want to explicitly include them in your project file.
To resolve the errors, do one of the following:
Remove the explicit
Compile
,EmbeddedResource
, orNone
items that match the implicit ones listed on the previous table.Set the EnableDefaultItems property to
false
to disable all implicit file inclusion:XML<PropertyGroup> <EnableDefaultItems>false</EnableDefaultItems> </PropertyGroup>
If you want to specify files to be published with your app, you can still use the known MSBuild mechanisms for that, for example, the
Content
element.Selectively disable only
Compile
,EmbeddedResource
, orNone
globs by setting the EnableDefaultCompileItems, EnableDefaultEmbeddedResourceItems, or EnableDefaultNoneItems property tofalse
:XML<PropertyGroup> <EnableDefaultCompileItems>false</EnableDefaultCompileItems> <EnableDefaultEmbeddedResourceItems>false</EnableDefaultEmbeddedResourceItems> <EnableDefaultNoneItems>false</EnableDefaultNoneItems> </PropertyGroup>
If you only disable
Compile
globs, Solution Explorer in Visual Studio still shows *.cs items as part of the project, included asNone
items. To disable the implicitNone
glob, setEnableDefaultNoneItems
tofalse
too.
You might hit this error in a WPF project due to duplicate ApplicationDefinition
or Page
items. To resolve the error, can you disable default items using an MSBuild property. For example, to disable default Page
items in a WPF project, set EnableDefaultPageItems
to false
:
<PropertyGroup>
<EnableDefaultPageItems>false</EnableDefaultPageItems>
</PropertyGroup>
For more information, see Errors related to duplicate items (WPF).
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