Why is the header not working in this code? - php

Question

The php code to get to the header after executing the queries
<?php
if (isset($_POST['Submit1'])) {
$con = mysqli_connect("localhost:3306", "root", "", "travels");
// Check connection
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$fname1 = $_POST['fname'];
$lname1 = $_POST['lname'];
$pnum1 = $_POST['pnum'];
$email1 = $_POST['email'];
$fcode = $_POST['fcode'];
$sql = "insert into customer_info(fname,lname,pnumber,email) values ('$fname1','$lname1','$pnum1','$email1')";
$sql1 = "insert into booking_info(fname,lname,pnumber,email,f_code) values ('$fname1','$lname1','$pnum1','$email1','$fcode')";
$sql2 = "update flight_info set seats_available=seats_available-1 where flight_code='$fcode'";
mysqli_query($con, $sql);
mysqli_query($con, $sql1);
mysqli_query($con, $sql2);
header("Location: Booking_confirm.php");
}
?>
HTML CODE
<div class="container mt-5">
<div class="row">
<div class="col-md-6">
<form action="Booking.php" method="POST">
<div class="form-group">
<label for="fname">First Name: </label>
<input type="text" name="fname" class="form-control" id="fname"/>
</div>
<div class="form-group">
<label for="lname">Last Name: </label>
<input type="text" name="lname" class="form-control" id="lname"/>
</div>
<div class="form-group">
<label for="pnum">Phone Number: </label>
<input type="text" name="pnum" class="form-control" id="pnum"/>
</div>
<div class="form-group">
<label for="email">Email-Address: </label>
<input type="text" name="email" class="form-control" id="email"/>
</div>
<div class="form-group">
<label for="flight">Flight No: </label>
<input type="text" name="fcode" class="form-control" id="fcode"/>
</div>
<form action="Booking_confirm.php" method="POST" target="_blank">
<button type="Submit" name="Submit1" class="btn btn-primary">Book</button>
</form>
</form>
</div>
This is how my code looks. for some reason my header is not working and i am not able to find out why.
Help would be appreciated.
I have tried every possible change to get the header to work but of no use

Answer 1

You have two nested forms, your first form action="Booking.php" contains all fields while the second, nested form action="Booking_confirm.php", only contains the submit button an NO fields.
Replace
<form action="Booking_confirm.php" method="POST" target="_blank">
<button type="Submit" name="Submit1" class="btn btn-primary">Book</button>
</form>
with
<button type="Submit" name="Submit1" class="btn btn-primary">Book</button>
When clicking submit there is no $_POST['fname'], $_POST['lname'] etc.
Edit: you also might need to replace
<form action="Booking.php" method="POST">
with
<form action="Booking_confirm.php" method="POST" target="_blank">
depending on where your "header"/code is placed

Answer 2

Make sure there is not white space or html tags or any output, before the header() function...
upload the entire code, structure so we can help you find the solution