例外のハンドリング

try
{

}
catch (Exception ex)
{
    if (ex is COMException)
    {
        COMException exCOM = (COMException)ex;
        MessageBox.Show(exCOM.Message, "エラー(" + exCOM.ErrorCode.ToString() +eBoxButtons.OK, MessageBoxIcon.Error);
    }
    else
    {
        MessageBox.Show(ex.Message, "エラー", MessageBoxButtons.OK, MessageBoxIcon.Error);
    } 
}
Try

Catch ex As Exception
    If (TypeOf ex Is System.Runtime.InteropServices.COMException) Then
        Dim exCOM As System.Runtime.InteropServices.COMException = CType(ex, Sysime.InteropServices.COMException)
        MessageBox.Show(exCOM.ErrorCode.ToString() + Environment.NewLine + exCOM, "エラー", MessageBoxButtons.OK, MessageBoxIcon.Error)
    Else
        MessageBox.Show(ex.Message)
    End If
End Try

'エラーコード
http://resources.arcgis.com/en/help/arcobjects-net/conceptualhelp/#/ArcObjects_error_codes/0001000002zz000000/