Value cannot be null. Parameter name: source?

Question

private void cbNomSociete_SelectedIndexChanged(object sender, EventArgs e)
{

  dgvListeAssemblee.DataSource = (
    from x in ListAssemble
    where x.Denomination
           .ToUpper()
           .Contains( cbNomSociete.SelectedItem.ToString().ToUpper() )
    select x
    ).ToList() ;

 }

how can this be fixed please

This looks like a few other stack questions for example: http://stackoverflow.com/questions/16281133/value-cannot-be-null-parameter-name-source OR http://stackoverflow.com/questions/3244336/using-linq-to-find-item-in-a-list-but-get-value-cannot-be-null-parameter-name — drew_w, May 07 '14 at 22:11
Debug it in Visual Studio. Enable the option "Break when exception is thrown" and you'll get the callstack. — Thomas Weller, May 07 '14 at 22:11

score 0 · Answer 1 · answered May 07 '14 at 22:18

how can this be fixed please

Figure out which variable/property is null. Based on the error message, the exception is likely coming from a static Linq extension method (since they all have a first parameter named source), which would mean the most likely candidate is ListAssemble.

If x.Denomination or cbNomSociete.SelectedItem were null you'd see a different error message.

Value cannot be null. Parameter name: source?

1 Answers1