Could not load assembly System.Runtime.CompilerServices.Unsafe

I am working on .NET Core app + NET Standard 2 library. This library uses EntityFrameworkCore.SQLServer. When I added yet EntityFrameworkCore.PostgreSQL then app during the start gives me an error:

... Microsoft.EntityFrameworkCore.Query.Internal.AsyncLinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExce ptionInterceptor.MoveNext(CancellationToken cancellationToken) System.IO.FileLoadException: Could not load file or assembly 'System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1, C ulture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) File name: 'System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' at Npgsql.NpgsqlWriteBuffer.Write[T](T value)

I have reinstalled the EntityFrameworkCore.PostgreSQL - not fixed. May be I can add this assembly to my library but where I can get it: 'System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1, C ulture=neutral, PublicKeyToken=b03f5f7f11d50a3a'

Thanx.