Ho modificato cosi e funziona

codice:
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            DataRowView drv = (DataRowView)e.Row.DataItem;
            string sVal = drv.Row["id"].ToString();

            HyperLink HyperLink1 = (HyperLink)e.Row.FindControl("HyperLink1");
            HyperLink1.Text = "Apri";
            HyperLink1.NavigateUrl = "javascript:info('" + sVal + "');";
            //HyperLink1.Attributes.Add("onClick", "javascript:info('"+sVal+"');");
        }
    }



<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:con %>" SelectCommand="SELECT * FROM [tb_paging]"></asp:SqlDataSource>
        <asp:GridView ID="GridView1" runat="server" AllowPaging="True" AutoGenerateColumns="False" DataKeyNames="id" DataSourceID="SqlDataSource1" PageSize="5" onRowDataBound="GridView1_RowDataBound">
            <Columns>
                <asp:BoundField DataField="id" HeaderText="id" InsertVisible="False" ReadOnly="True" SortExpression="id" />
                <asp:BoundField DataField="testo" HeaderText="testo" SortExpression="testo" />
                <asp:TemplateField HeaderText="link">                  
                  <ItemTemplate>
                    <asp:HyperLink ID="HyperLink1" runat="server"></asp:HyperLink>
                  </ItemTemplate>
                </asp:TemplateField>    
                
            </Columns>
        </asp:GridView>
Se puoi mi controlli lo script, modificandolo cosi funziona.

Grazie 1000