GridView OnSelectedIndexChanged event not firing

If you are just clicking on the row in the GridView, that will not fire the event. You have to have some kind of button in the row to click on, which will fire the RowCommand event, as well as the SelectedIndexChanged event (if the row you click is not already selected, of course). It's not exactly like the Windows Forms DataGridView =)

The easiest way to get the event to fire, is to add this attribute to your GridView markup:

AutoGenerateSelectButton="True"

This creates a "Select" LinkButton, which will fire the Gridview1_SelectedIndexChanged2 event in your code-behind when you click it.

EDIT: Just to clarify, this is where you need to add that attribute:

<asp:GridView ID="GridView1" runat="server" GridLines="None" 
  Width="930px" CellPadding="4" ForeColor="#333333"  
  onselectedindexchanged="GridView1_SelectedIndexChanged2"
  AutoGenerateSelectButton="True" >

It's been a few years since this question was asked and I certainly hope the person with the problem got it figured out but I had the same problem and thanks to one of the responders I figured out what the problem was.

Check the actual button line in the Gridview and make sure that you have the CommandName="Select" in the ButtonField. For some reason that code, which is normally entered automatically wasn't added.

If you have postback code in selected index changing method you should false EnableEventValidation

  <%@ Page Title="" Language="C#" EnableEventValidation="false" MasterPageFile="~/Administration/Site.master" AutoEventWireup="true" CodeFile="CourseStatusReport.aspx.cs" Inherits="Administration_Reports_CourseStatusReport" %>

It is NOT true that you can't click a row and have it handle the SelectedIndexChanged event. You just have to add a little code to the RowCreated event.

Protected Sub yourDataGrid_RowCreated(sender As Object, e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles yourDataGrid.RowCreated
    If e.Row.RowType = DataControlRowType.DataRow Then
        e.Row.Attributes("onclick") = Me.Page.ClientScript.GetPostBackEventReference(Me.yourDataGrid, "Select$" & e.Row.RowIndex)
    End If
End Sub