Hi,
change your above code to following.
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack)
{
string user = Convert.ToString(Session["user"]);
if (user != null)
{
signin_btn.Text = "sign out";
lbl_email.Text = Convert.ToString(Session["user"]);
}
else if(user==null)
{
signin_btn.Text = "Sign in";
Response.Redirect("login.aspx");
}
}
}
protected void signin_btn_Click(object sender, EventArgs e)
{
string user = Convert.ToString(Session["user"]);
if (user != null && signin_btn.Text == "sign out")
{
Session.Clear();
Session.Abandon();
signin_btn.Text = "sign in";
Response.Redirect("login.aspx");
}
}
Hope it helps.