hello I see this error and I do not know what I forgot to install in visual study so that I would appear 
hello I see this error and I do not know what I forgot to install in visual study so that I would appear
You have to go to the root of the project, open the .csprj and delete this line:
<ItemGroup>
<Compile Include="carpeta\Namespace\persona.cs" />
</ItemGroup>
At some point you will have touched the properties of that class.