具有NET标准2.0的引用项目的UWP（UAP 10.0.16299）出现LINQ（IEnumerable）问题

Question

I face a problem with my UWP application. I have the client UWP (target version is Windows 10 Fall Creator Update 10.0.16299 and same for min version ) which reference 2 other projects Net standard 2.0

I get those errors in AppShell.cs and some other Page :

Severity Code Description Project File Line Suppression State Error CS0012 The type 'IEnumerable<>' is defined in an assembly that is not referenced. You must add a reference to assembly 'netstandard, Version=2.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'.

the lines where are the problem are all about link :

var item = (from p in PrimaryMenuItems where p.DestPage == e.SourcePageType select p).SingleOrDefault();

I really don't understand why.

Answer 1

It might be that NuGet Packages were not correctly restored. Close Visual Studio and delete all bin and obj folders in your solution. Then open your solution again and right-click on the solution in Solution Explorer and select Restore NuGet Packages . The errors should go away after that.

Answer 2

Finally after many hours, I just understood and found the solution to this tricky issue. In my UWP project file (.csproj) , the version of the referenced Microsoft.NETCore.UniversalWindowsPlatform was 5.3.3, I replaced it by 6.1.5 and it works.