"Please Wait" Form not rendering when called

Question

I am writing a program which does a lot of processes at once. To keep the user from thinking the program crashed, I decided to add a "Please Wait" window. Everything works fine except for one thing: the form doesn't fully render until 30 seconds later. Before that the "Please wait until..." text that is supposed to be in the form is just a white rectangle.

Can you please tell me how I can fix this issue? Thanks!

Edit:

As I assumed everyone had a crystal ball and could read my virtual mind, I forgot to include the code >.>;;

Here it is:

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    Dim pleasewait As New TestEspere
    CenterForm(pleasewait)
    pleasewait.Show()
    Dim quantity, quantity_purchased As Integer
    Dim tracking_usps, lybro_id, recipient_name, order_id, order_item_id, payments_transaction_id, product_id, description, listing_id, sku,
           batch_id, buyer_email, buyer_name, address_1, address_2,
        city, state, zip, country, special_comments, upc, status_shipment, loc, tracking, etc, eff As String
    Dim total_price, peso, order_price, shipping_price As Decimal
    Dim purchase_date, payments_date As Date

    For i = 0 To DataGridView1.Rows.Count - 1
        On Error GoTo netx
        If IsDBNull(DataGridView1(0, i).Value) Then Exit For
        DataGridView1(33, i).Value = TrackingRequest(Replace(DataGridView1(32, i).Value, "'", ""))

        lybro_id = DataGridView1(0, i).Value
        order_id = DataGridView1(1, i).Value
        order_item_id = If(IsDBNull(DataGridView1(2, i).Value), "", DataGridView1(2, i).Value)
        payments_date = String.Format("{0:yyyy-MM-dd}", DataGridView1(3, i).Value.ToString)
        quantity = DataGridView1(4, i).Value
        payments_transaction_id = If(IsDBNull(DataGridView1(5, i).Value), "", DataGridView1(5, i).Value)
        product_id = DataGridView1(6, i).Value
        description = Replace(DataGridView1(7, i).Value, "'", "''")
        peso = DataGridView1(8, i).Value
        listing_id = If(IsDBNull(DataGridView1(9, i).Value), "", DataGridView1(9, i).Value)
        sku = DataGridView1(10, i).Value
        order_price = DataGridView1(11, i).Value
        shipping_price = DataGridView1(12, i).Value
        quantity_purchased = DataGridView1(13, i).Value
        total_price = DataGridView1(14, i).Value
        purchase_date = String.Format("{0:yyyy-MM-dd}", DataGridView1(15, i).Value.ToString )
        batch_id = If(IsDBNull(DataGridView1(16, i).Value), "", DataGridView1(16, i).Value)
        buyer_email = DataGridView1(17, i).Value
        buyer_name = Replace(DataGridView1(18, i).Value, "'", "''")
        recipient_name = Replace(DataGridView1(19, i).Value, "'", "''")
        address_1 = Replace(DataGridView1(20, i).Value, "'", "''")
        address_2 = If(IsDBNull(DataGridView1(21, i).Value), "", DataGridView1(21, i).Value)
        city = Replace(DataGridView1(22, i).Value, "'", "''")
        state = If(IsDBNull(DataGridView1(23, i).Value), "", Replace(DataGridView1(23, i).Value, "'", "''"))
        zip = DataGridView1(24, i).Value
        country = Replace(DataGridView1(25, i).Value, "'", "''")
        special_comments = If(IsDBNull(DataGridView1(26, i).Value), "", Replace(DataGridView1(26, i).Value, "'", "''"))
        upc = If(IsDBNull(DataGridView1(27, i).Value), "", DataGridView1(27, i).Value)
        etc = If(IsDBNull(DataGridView1(28, i).Value), "", DataGridView1(28, i).Value)
        status_shipment = DataGridView1(29, i).Value
        loc = Replace(DataGridView1(30, i).Value, "'", "''")
        eff = If(IsDBNull(DataGridView1(31, i).Value), "", DataGridView1(31, i).Value)
        tracking = If(IsDBNull(DataGridView1(32, i).Value), "", DataGridView1(32, i).Value)
        tracking_usps = Replace(DataGridView1(33, i).Value, "'", "''")

        Cmd.CommandText = String.Format("INSERT INTO re_orders_con_pesos(re_lybro_id, re_order_id, re_order_item_id, re_payments_date, re_quantity, re_payments_transaction_id, re_product_id,
                            re_description, re_peso, re_listing_id, re_sku, re_order_price, re_shipping_price, re_quantity_purchased, re_total_price, re_purchase_date, re_batch_id, re_buyer_email,
                            re_buyer_name, re_recipient_name, re_ship_address_1, re_ship_address_2, re_ship_city, re_ship_state, re_ship_zip, re_ship_country, re_special_comments, re_upc, re_etc, re_status_shipment,
                            re_location, re_eff, re_tracking, re_tracking_usps, re_status_email, re_status_db) VALUES('{0}','{1}','{2}','{3}','{4}','{5}','{6}','{7}','{8}','{9}','{10}','{11}','{12}','{13}','{14}','{15}','{16}','{17}','{18}','{19}','{20}',
                            '{21}','{22}','{23}','{24}','{25}','{26}','{27}','{28}','{29}','{30}','{31}','{32}', '{33}','{34}','{35}')", lybro_id, order_id, order_item_id, payments_date, quantity, payments_transaction_id,
                                        product_id, description, peso, listing_id, sku, order_price, shipping_price, quantity_purchased, total_price, purchase_date, batch_id, buyer_email,
                                        buyer_name, recipient_name, address_1, address_2, city, state, zip, country, special_comments, upc, etc, status_shipment, loc, eff, tracking, tracking_usps,
                                        ESTATUS_EMAIL_NUEVO, ESTATUS_DB_NUEVO)
        Cmd.Execute()
netx:
    Next

    pleasewait.Close()

    Beep()
End Sub

Answer 1

The code for the button click event handler is run on the UI's thread. This thread is supposed to handle your display only, but you are moving data around on it and using it to store information to your database. There is simply too much wrong to attempt to solve all your problems, so I, and the other commenters, propose a band-aid: Application.DoEvents. The placement below will allow your UI to respond to your events and update before you process each row in the datagridview.

Also, on error goto is deprecated, so I replaced it with the newer functional equivalent Try .. Catch

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    Dim pleasewait As New TestEspere
    CenterForm(pleasewait)
    pleasewait.Show()
    ' ... (code removed for brevity)

    For i = 0 To DataGridView1.Rows.Count - 1
        ' This call will allow your pleasewait form to update
        Application.DoEvents()
        Try
            If IsDBNull(DataGridView1(0, i).Value) Then Exit For
            DataGridView1(33, i).Value = TrackingRequest(Replace(DataGridView1(32, i).Value, "'", ""))
            lybro_id = DataGridView1(0, i).Value
            ' ... (code removed for brevity)
            tracking_usps = Replace(DataGridView1(33, i).Value, "'", "''")
            Cmd.CommandText = String.Format("INSERT INTO re_orders_con_pesos(re_lybro_id, re_order_id, re_order_item_id, re_payments_date, re_quantity, re_payments_transaction_id, re_product_id,
                        re_description, re_peso, re_listing_id, re_sku, re_order_price, re_shipping_price, re_quantity_purchased, re_total_price, re_purchase_date, re_batch_id, re_buyer_email,
                        re_buyer_name, re_recipient_name, re_ship_address_1, re_ship_address_2, re_ship_city, re_ship_state, re_ship_zip, re_ship_country, re_special_comments, re_upc, re_etc, re_status_shipment,
                        re_location, re_eff, re_tracking, re_tracking_usps, re_status_email, re_status_db) VALUES('{0}','{1}','{2}','{3}','{4}','{5}','{6}','{7}','{8}','{9}','{10}','{11}','{12}','{13}','{14}','{15}','{16}','{17}','{18}','{19}','{20}',
                        '{21}','{22}','{23}','{24}','{25}','{26}','{27}','{28}','{29}','{30}','{31}','{32}', '{33}','{34}','{35}')", lybro_id, order_id, order_item_id, payments_date, quantity, payments_transaction_id,
                                    product_id, description, peso, listing_id, sku, order_price, shipping_price, quantity_purchased, total_price, purchase_date, batch_id, buyer_email,
                                    buyer_name, recipient_name, address_1, address_2, city, state, zip, country, special_comments, upc, etc, status_shipment, loc, eff, tracking, tracking_usps,
                                    ESTATUS_EMAIL_NUEVO, ESTATUS_DB_NUEVO)
            Cmd.Execute()
        Catch
            ' you are ignoring exceptions, but this is where you should be handling them!
        End Try
    Next

    pleasewait.Close()
    Beep()
End Sub

Under normal circumstance, I can't think of a reason to ever use Application.DoEvents. In your case, a solution without it would require too significant a rewrite to your application.