I am experiencing an issue that I have never seen before. I opened an old application (I believe it was created with VS 2015) in Visual Studio 2019, and all Nuget packages show yellow triangles. I tried Update-Package -reinstall, I watch each package get reinstalled, and they still show yellow triangles. I tried uninstalling and reinstalling using Nuget Package Manager and as soon as the package is installed it shows the yellow triangle. I tried deleting the reference and manually adding the dll from packages folder in the solution, and I get the same thing.
I saw a post where someone suggested removing the following from the project file:
<Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" /><Import Project="$(VSToolsPath)\WebApplications\Microsoft.WebApplication.targets" Condition="'$(VSToolsPath)' != ''" /><Target Name="MvcBuildViews" AfterTargets="AfterBuild" Condition="'$(MvcBuildViews)'=='true'"><AspNetCompiler VirtualPath="temp" PhysicalPath="$(WebProjectOutputDir)" /></Target>Which also didn't work. I also tried adding packages that didn't already exist in the app, and after installing they too show with a yellow triangle. Also, all packages show Copy Local = False.
Any suggestions are greatly appreciated.