Could you please change the ConvertIdFromString method to return using this code in the Microsoft.AspNetIdentity.Owin.SignInManager class:
return (TKey)TypeDescriptor.GetConverter(typeof(TKey)).ConvertFromInvariantString(id);
I downloaded the source code, made this change on my local. However, when I try to run my project with this new update I get an error about StrongName verification.