ServiceStack with .Net Framework SameSite Error

You’ll need to set the new HttpCookie.SameSite property which requires upgrading to .NET Framework v4.7.2, you can set by overriding HttpCookieFilter in your AppHost, e.g:

public override void HttpCookieFilter(HttpCookie cookie)
{
    cookie.SameSite = SameSiteMode.None;
}