Not able to connect to database in ASP IIS - asp.net

Question

I was able to deloy my asp project on IIS and it shows the front page, there I have a login page , after entering the credentials it does not logs in, I used try and catch , and in catch it gave me an error, stating thread has aborted, it was on
page.redirect["master.apsx",true]
so I changed it to
page.redirect["master.aspx",false]
and it didnt gave error, but it was not able to login further, I guess it is not able to connect to database. So any help would be appreciable.
Thanks
CODE:
protected void Page_Load(object sender, EventArgs e)
{
strconn = #"Data Source=.\SQLEXPRESS;AttachDbFilename=" + Server.MapPath("~/App_Data/Securityservice.mdf") + ";Integrated Security=True;User Instance=True";
Label1.Text = " conn string";
}
protected void Button2_Click(object sender, EventArgs e)
{
}
protected void btn_popup_quick_login_Click(object sender, EventArgs e)
{
try
{
if (txt_username.Text != null)
{
if (txt_password.Text != null)
{
DataTable dt = new DataTable();
conn = new SqlConnection(strconn);
conn.Open();
cmd = new SqlCommand("Select * From UserMaster Where Username=#username and Password=#password", conn);
cmd.Parameters.AddWithValue("#username", txt_username.Text);
cmd.Parameters.AddWithValue("#password", txt_password.Text);
da = new SqlDataAdapter(cmd);
da.Fill(dt);
{
if (dt.Rows.Count > 0)
{
userloginname = txt_username.Text;
userloginpassword = txt_password.Text;
Session["username"] = txt_username.Text;
MessageBox.Show("User Login Sucessfully", "Login", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
Response.Redirect("Marketing.aspx",false);
}
else
{
Label1.Text = "else part";
MessageBox.Show("Invalid User Name and Password", "Login", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
txt_username.Focus();
}
txt_username.Text = "";
txt_password.Text = "";
}
}
}
}
catch (Exception ex) { MessageBox.Show(ex.Message,"Error",MessageBoxButtons.OK,MessageBoxIcon.Error); }
conn.Close();
Label1.Text = "login";
}

Answer 1

You should check the connection strings in web.config, to make sure they still point to the proper location of the database after you deployed the site.

Answer 2

I think the problem could be the Application_Start method.
Look if you have written some thing there.
Make a break point there and see is there any error.
Or have you written Response.End() in you code?
You need to provide more detail
You need to check weather you are able to connect to database or not.
You also need to check weather the page is called or not (which comes after login).