PHP Update operation showing network ERROR

Question

I am working on a simple php crud operation for a database table. I follow one crud project available in https://codeshack.io/crud-application-php-pdo-mysql/ this url. But for my sql database I edit the code.

The read, delete and create operations are working perfect after modifying the code for my database table. --->> But Update operation is not working when i try to update!!! I tried to find out the problem but I can't see any problem in the code.

here is my update code after modification for my table name Film where there are 14 attributes. The primary key of the table Film is Film_ID.

<?php
include 'functions.php';
$pdo = pdo_connect_mysql();
$msg = '';
// Check if the Film id exists, for example update.php?id=1 will get the film with the id of 1
if (isset($_GET['Film_ID'])) {
    if (!empty($_POST)) {
        // This part is similar to the create.php, but instead we update a record and not insert
        $Film_ID = isset($_POST['Film_ID']) ? $_POST['Film_ID'] : NULL;
        $LanguageID = isset($_POST['LanguageID']) ? $_POST['LanguageID'] : '';
        $RegionID = isset($_POST['RegionID']) ? $_POST['RegionID'] : '';
        $Title = isset($_POST['Title']) ? $_POST['Title'] : '';
        $Description = isset($_POST['Description']) ? $_POST['Description'] : '';

        $Release_Year = isset($_POST['Release_Year']) ? $_POST['Release_Year'] : '';
        $Rental_Duration = isset($_POST['Rental_Duration']) ? $_POST['Rental_Duration'] : '';
        $Rental_Rate = isset($_POST['Rental_Rate']) ? $_POST['Rental_Rate'] : '';

        $Length = isset($_POST['Length']) ? $_POST['Length'] : '';
        $Replacement_Cost = isset($_POST['Replacement_Cost']) ? $_POST['Replacement_Cost'] : '';
        $Rating = isset($_POST['Rating']) ? $_POST['Rating'] : '';

        $Special_Features = isset($_POST['Special_Features']) ? $_POST['Special_Features'] : '';
        $FullText_Var = isset($_POST['FullText_Var']) ? $_POST['FullText_Var'] : '';

        $Last_Update = isset($_POST['Last_Update']) ? $_POST['Last_Update'] : date('Y-m-d H:i:s');
        // Update the record
        $stmt = $pdo->prepare('UPDATE Film 
                        SET Film_ID = ?, LanguageID = ?, 
                            RegionID = ?, Title = ?, 
                            Description = ?, Release_Year = ?, 
                            Rental_Duration = ?, Rental_Rate = ?, 
                            Length = ?, Replacement_Cost = ?, 
                            Rating = ?, Special_Features = ?,
                            FullText_Var = ?, Last_Update = ? 
                        WHERE id = ?');

        $stmt->execute([$Film_ID, $LanguageID, 
                        $RegionID, $Title, 
                        $Description, $Release_Year, 
                        $Rental_Duration, $Rental_Rate,
                        $Length, $Replacement_Cost, 
                        $Rating,$Special_Features, 
                        $FullText_Var, $Last_Update, 
                        $_GET['Film_ID']]);
        $msg = 'Updated Successfully!';
    }
    // Get the films from the Film table
    $stmt = $pdo->prepare('SELECT * FROM Film WHERE Film_ID = ?');
    $stmt->execute([$_GET['Film_ID']]);
    $films = $stmt->fetch(PDO::FETCH_ASSOC);
    if (!$films) {
        exit('Film doesn\'t exist with that ID!');
    }
} else {
    exit('No ID specified!');
}
?>

<?=template_header('Read')?>

<div class="content update">
    <h2>Update Films #<?=$films['Film_ID']?></h2>
    <form action="update.php?Film_ID=<?=$films['Film_ID']?>" method="post">
        <label for="Film_ID">FilmID</label>
        <input type="text" name="Film_ID" placeholder="1" value="<?=$films['Film_ID']?>" id="Film_ID">

        <label for="LanguageID">LanguageID</label>
        <input type="text" name="LanguageID" placeholder="1" value="<?=$films['LanguageID']?>" id="LanguageID">

        <label for="RegionID">RegionID</label>
        <input type="text" name="RegionID" placeholder="1" value="<?=$films['RegionID']?>" id="RegionID">

    
        <label for="Title">Title</label>
        <input type="text" name="Title" placeholder="Title" value="<?=$films['Title']?>" id="Title">
        <label for="Description">Description</label>
        <input type="text" name="Description" placeholder="Description" value="<?=$films['Description']?>" id="Description">

        <label for="Release_Year">Release_Year</label>
        <input type="text" name="Release_Year" placeholder="Release_Year" value="<?=$films['Release_Year']?>" id="Release_Year">
        <label for="Rental_Duration">Rental_Duration</label>
        <input type="text" name="Rental_Duration" placeholder="Rental_Duration" value="<?=$films['Rental_Duration']?>" id="Rental_Duration">

        <label for="Rental_Rate">Rental_Rate</label>
        <input type="text" name="Rental_Rate" placeholder="Rental_Rate" value="<?=$films['Rental_Rate']?>" id="Rental_Rate">
        <label for="Length">Length</label>
        <input type="text" name="Length" placeholder="Length" value="<?=$films['Length']?>" id="Length">

        <label for="Replacement_Cost">Replacement_Cost</label>
        <input type="text" name="Replacement_Cost" placeholder="Replacement_Cost" value="<?=$films['Replacement_Cost']?>" id="Replacement_Cost">
        <label for="Rating">Rating</label>
        <input type="text" name="Rating" placeholder="Rating" value="<?=$films['Rating']?>" id="Rating">

        <label for="Special_Features">Special_Features</label>
        <input type="text" name="Special_Features" placeholder="Special_Features" value="<?=$films['Special_Features']?>" id="Special_Features">
        <label for="FullText_Var">FullText_Var</label>
        <input type="text" name="FullText_Var" placeholder="FullText_Var" value="<?=$films['FullText_Var']?>" id="FullText_Var">
       
        <label for="Last_Update">Last_Update</label>
        <input type="datetime-local" name="Last_Update" value="<?=date('Y-m-d\TH:i', strtotime($films['Last_Update']))?>" id="Last_Update">
        <input type="submit" value="Update">
    </form>
    <?php if ($msg): ?>
    <p><?=$msg?></p>
    <?php endif; ?>
</div>

<?=template_footer()?>