How to solve the error "Must use PackageReference"?

Question

After adding WindowsRuntime to a WinForms-project, building the project fails with Error "Must use PackageReference". The build log is more precise:

C:[...]\Visual Studio 2017\Projects\Projectname\packages\Microsoft.Windows.SDK.Contracts.10.0.18362.2005\build\Microsoft.Windows.SDK.Contracts.targets(4,5): error : Must use PackageReference

Here's what I did:

Install-Package Microsoft.Windows.SDK.Contracts

with references to:

• C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETCore\v4.5\System.Runtime.WindowsRuntime.dll,
• C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\Facades\System.Runtime.dll
• C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\Facades\System.Threading.Tasks.dll
• C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\Facades\System.IO.dll
• C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework.NETFramework\v4.5\Facades\System.Runtime.InteropServices.WindowsRuntime.dll.

Is it maybe a thing with the .NET version? In the project's packages.config there is 4.6 while the project targets 4.5.

<?xml version="1.0" encoding="utf-8"?>
<packages>
<package id="Microsoft.Windows.SDK.Contracts" version="10.0.18362.2005" targetFramework="net45"/>
<package id="System.Runtime.WindowsRuntime" version="4.6.0" targetFramework="net45" />
<package id="System.Runtime.WindowsRuntime.UI.Xaml" version="4.6.0" targetFramework="net45" />
</packages>

There are no compile errors... only this strange "PackageReference" error.

Answer 1

VS2017/VS2019 -> Solution Explorer -> right-click References -> "Migrate packages.config to PackageReference"

VS2019 -> Solution Explorer -> right-click packages.config -> "Migrate packages.config to PackageReference"

I think this happens when you add a .NET core library to a .NET standard project.

Answer 2

Solution that worked for me was to:

1. Run a Clean on the project in question
2. Close Visual Studio
3. Navigate to the project folder on disk and delete the obj folder
4. Reopen Visual Studio and Build

Answer 3

Go to your .csproj and remove the references to the package. On my case they were at the end of the XML file