You are creating new instances
of connection
everytime you are accessing it. so create only one instance
and use it like this
OleDbConnection connection= ConnectDB.getConStr();
string query = "insert into users (memberName,memberSurname,memberEmail,userName,userPassword) values(@mn,@msn,@me,@un,@up)";
OleDbCommand cmd = new OleDbCommand( query,connection);
cmd.Parameters.AddWithValue("@mn", txtName.Text);
cmd.Parameters.AddWithValue("@msn", txtSurname.Text);
cmd.Parameters.AddWithValue("@me", txtEmail.Text);
cmd.Parameters.AddWithValue("@un", txtUsername.Text);
cmd.Parameters.AddWithValue("@up", txtPassword.Text);
try
{
connection.Open();
cmd.ExecuteNonQuery();
connection.Close();
ltrMesaj.Text = "Record has been added";
Response.Redirect("Login.aspx");
}
catch (Exception ex)
{
ltrMesaj.Text = ex.Message;
}