Object Reference not set to an instance of an Object?

Question

I’m tapping into the database and calling a procedure to insert into the bank but this error occurs you know the reason:

Code:

Dim con As SqlConnection = New SqlConnection()
Dim cmd As SqlCommand = New SqlCommand()

con = Nothing
cmd = Nothing

Try

    con.ConnectionString = "Server = ;Database=;User Id=;Password = ;"

    con.Open()
    cmd.Connection = con
    cmd = New SqlCommand("prdInserirRegistro", con)
    cmd.CommandType = CommandType.StoredProcedure

    cmd.Parameters.Add(New SqlParameter("@dtLog", SqlDbType.DateTime))
    cmd.Parameters.Add(New SqlParameter("@dsLog", SqlDbType.VarChar, 1000))

    'recebe o parâmetro selecionado na combobox
    cmd.Parameters("@dtLog").Value = Now
    cmd.Parameters("@dsLog").Value = txtBoxLog.Text


    cmd.ExecuteNonQuery()

Catch ex As Exception
    MsgBox("erro em: " & ex.Message)
Finally

    If Not con Is Nothing Then
        con.Close()
        con.Dispose()
    End If
    con = Nothing

    If Not cmd Is Nothing Then
        cmd.Dispose()
    End If
    cmd = Nothing

Answer 1

You gotta take that con = Nothing. In fact the code is very confused, doing nonsense things, it may be that solving this error find other.

Dim con As SqlConnection = New SqlConnection() //criou o objeto
Dim cmd As SqlCommand = New SqlCommand()
con = Nothing // ===============================>abandonou objeto
cmd = Nothing
Try
    'Aqui tenta acessar o objeto que não existe, por isso dá esse erro
    con.ConnectionString = "Server = ;Database=;User Id=;Password = ;"

I put in the Github for future reference.

Answer 2

Your code is in that order:

1. Dim cmd As SqlCommand = New SqlCommand()

2. cmd = Nothing

3. cmd.Connection = con

---

1. Dim con As SqlConnection = New SqlConnection()

2. con = Nothing

3. con.ConnectionString = "Server = ;Database=;User Id=;Password = ;"

---

In the second step you assign con and cmd to Nothing.

Therefore, the references they had of the instances of the classes created in step 1 are lost.

Remove the snippets from item 2 (con = Nothing and cmd = Nothing)