Getting error when reffering .NET core project to WCF

I have .NET EF core (target Framework .NET core 2.0) project which involves only entities. This project is refereed in other .NET core project but also in a WCF application (having target Framework .NET 4.6.1), since I need to connect to the database. For some reason each time when I tried to access the database from WCF application I have the following error:

System.IO.FileLoadException: 'Could not load file or assembly 'System.Runtime, Version=4.2.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)'

Do you know what could be the reason for this ? As I know, I should be able to refer .NET core project into .NET 4.6 WCF project..

Thanks alot