The GridView 'GridView1' fired event PageIndexChanging which wasn't handled

This error is caused when an aspx page contains a GridView which has pagination enabled, but the PageIndexChanging event has not been handled.

This had me stumped for a short while today whilst coding a C# ASP.NET web application. If you have pagination turned on, you'll need to create a handler for your GridView, thus:

protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
{                                             

      // Increment Page Index
      GridView1.PageIndex = e.NewPageIndex;
                                                                  
      // Need to rebind or page does not change
      GridView1.DataSource = MyDataSet;
      GridView1.DataBind();

}

Note that in the above example I also explicitly set the new PageIndex, and rebind the DataSource. The reason being that if you don't, changing pages doesn't work.