Problem in saving many-to-many relationship with Entity Framework Core

I'm having trouble saving a many-to-many relationship with Entity Framework Core

I have the following entities

[Table("quadros")]
public class Quadro : BaseEntity
{
    public bool Ativo { get; set; }
    public string Titulo { get; set; }
    public List<CheckList> Checklists { get; set; }
    public bool Concluido { get; set; }
    public DateTime DataUltimaOperacao { get; set; }
    public List<UsuarioQuadro> Usuarios { get; set; }
    public long EmpresaId { get; set; }
    public Empresa Empresa { get; set; }
    public List<Atividade> Atividades { get; set; }
}


[Table("usuarios")]
public class Usuario : BaseEntity
{
    public bool Ativo { get; set; }
    public string Nome { get; set; }
    public string SobreNome { get; set; }
    public string Email { get; set; }
    public string Login { get; set; }
    public string Senha { get; set; }
    public int TipoUsuario { get; set; }
    public long EmpresaId { get; set; }
    public Empresa Empresa { get; set; }
    public List<UsuarioQuadro> Quadros { get; set; }
    public List<Atividade> Atividades { get; set; }
}

Relationship entity

[Table("usuarioQuadro")]
public class UsuarioQuadro : BaseEntity
{
    public Usuario Usuario { get; set; }
    public long UsuarioId { get; set; }
    public Quadro Quadro { get; set; }
    public long QuadroId { get; set; }
}

My DataContext

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
 modelBuilder.Entity<UsuarioQuadro>()
     .HasKey(uq => new { uq.UsuarioId, uq.QuadroId });  
   modelBuilder.Entity<UsuarioQuadro>()
        .HasOne(u => u.Usuario)
        .WithMany(uq => uq.Quadros)
        .HasForeignKey(u => u.UsuarioId)  
    modelBuilder.Entity<UsuarioQuadro>()
        .HasOne(q => q.Quadro)
        .WithMany(uq => uq.Usuarios)
        .HasForeignKey(u => u.QuadroId);
}

But when I save the frame with the users I get the following Exeception

  

System.InvalidOperationException: 'The property' UserId 'on entity type' UserAccount 'has a temporary value. Either set a permanent value explicitly or ensure that the database is configured to generate values for this property. '