How to disable PostBack when we click refresh button

Redirect your page back to itself, then the refresh will do the redirect, not the postback.

Want a simple working solution?
This one works perfectly with multiple clicks on button and so on.
http://csharpdotnetfreak.blogspot.com/2008/12/detect-browser-refresh-to-avoid-events.html
PS. No it's not an ad for my solution, just want to help

public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
Session["CheckRefresh"] =
Server.UrlDecode(System.DateTime.Now.ToString());
}
}
protected void Button1_Click(object sender, EventArgs e)
{
if (Session["CheckRefresh"].ToString() ==
ViewState["CheckRefresh"].ToString())
{
Label1.Text = "Hello";
Session["CheckRefresh"] =
Server.UrlDecode(System.DateTime.Now.ToString());
}
else
{
Label1.Text = "Page Refreshed";
}
}
protected void Page_PreRender(object sender, EventArgs e)
{
ViewState["CheckRefresh"] = Session["CheckRefresh"];
}
}

Why you do not use Ajax. I thing Ajax will be good for you.

Check the article
Stop Refresh after Submitting your Request[^]

cheers

// declare a global variable on page
private Boolean IsPageRefresh = false;

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
ViewState["postids"] = System.Guid.NewGuid().ToString();
Session["postid"] = ViewState["postids"].ToString();
TextBox1.Text = "Hi";

}
else
{
if (ViewState["postids"].ToString() != Session["postid"].ToString())
{
IsPageRefresh = true;
}
Session["postid"] = System.Guid.NewGuid().ToString();
ViewState["postids"] = Session["postid"];
}
}
protected void Button1_Click(object sender, EventArgs e)
{
if (!IsPageRefresh) // check that page is not refreshed by browser.
{
TextBox2.Text = TextBox1.Text + "@";

}
}

You should add validation before adding value to grid. Alternatively you can clear textbox value after submitting data.