Ggtcf

Newbie question: What exactly needs to be initialized to prevent a NullReferenceException? I don't understand what the variable is. What object reference do I need to set to an instance of what object? Thank you!

.aspx

 <p>
 <asp:GridView ID="gvConvo" runat="server" AutoGenerateColumns="False" OnSelectedIndexChanged="gvConvo_SelectedIndexChanged">
 <Columns>
 <asp:TemplateField HeaderText="ID">
 <ItemTemplate>
 <asp:LinkButton ID="lbtnConvo" OnClick="lbtnConvo_Click" Text='<%#Eval("ConvoUID") %>' runat="server">LinkButton</asp:LinkButton>
 </ItemTemplate>
 </asp:TemplateField>
 <asp:BoundField DataField="Convo" HeaderText="Convo" />
 <asp:BoundField DataField="ConvoDate" HeaderText="Date" />
 <asp:BoundField DataField="ConvoDesc" HeaderText="Description" />
 <asp:BoundField DataField="ConvoType" HeaderText="Type" />
 <asp:BoundField DataField="MediaSource" HeaderText="Media Source" />
 </Columns>
 </asp:GridView>
 </p>
 <p>
 &nbsp;</p>
 <p>
 Convo:
 <asp:TextBox ID="txtConvoSelection" runat="server" OnTextChanged="txtConvoSelection_TextChanged"></asp:TextBox>
 </p>

.cs

 protected void Page_Load(object sender, EventArgs e)
 
 if (!IsPostBack)
 
 string PersuasionDBCon = ConfigurationManager.ConnectionStrings["PersuasionDBCon"].ConnectionString;
 using (SqlConnection con = new SqlConnection(PersuasionDBCon))
 
 SqlCommand cmd = new SqlCommand("GetConvo", con);
 cmd.CommandType = CommandType.StoredProcedure;
 con.Open();
 gvConvo.DataSource = cmd.ExecuteReader();
 gvConvo.DataBind();
 
 
 

 protected void lbtnConvo_Click(object sender, EventArgs e)
 
 txtConvoSelection.Text = gvConvo.SelectedRow.Cells[1].Text;
 

 protected void BtnSaveQuote_Click(object sender, EventArgs e)
 

 

 protected void gvConvo_SelectedIndexChanged(object sender, EventArgs e)
 

 

 protected void txtConvoSelection_TextChanged(object sender, EventArgs e)
 

 

This is the line that's throwing the exception:

txtConvoSelection.Text = gvConvo.SelectedRow.Cells[1].Text;

The code to load the grid is surrounded by an if (!IsPostBack) block. Guess what? The button click event causes a postback. That's how it runs. And every time you do a postback, the entire page starts over from scratch. That's how HTTP works.

So when you click the button, the data for the grid is not bound, and there is no selected row.

The best fix for this is to make this happen in javascript, rather than C#. Reserve server events for things that really need to do work on the server. That will greatly improve perceived performance (no waiting for round-trips to a potentially-distant server) and help your server scale to handle more users by not needing to rebuild the entire html document for simple changes.

Index starts from 0
gvConvo.SelectedRow.Cells[1] this field must be null

Try

gvConvo.SelectedRow.Cells[0]

Also check for gvConvo.SelectedRow
may be there is no selected in Grid