Error:
C:\\WebApp\\WebApp.csproj : error : The SDK \'Microsoft.NET.Sdk.Web\' specified could not be found. C:\\WebApp\\WebApp.csproj
I have solved this issue by, go to this site, https://dotnet.microsoft.com/download In that, install both .NET Core Runtime and .NET Core SDK. After you install that, Open the Visual Studio 2017 with an administrator, Now The problem has been gone