Hey guys I'm still learning PHP and need help. I have 3 files that require a database.php file to connect to MySQL. when I execute the files only two of them work. For the last file, I get an HTTP error 500.
    <?php
      require( 'database.php');  
   // inserting information from the form into the database
   $sql = ("INSERT INTO guestlist (firstName, lastName, phoneNumber,guests,event)
      VALUES (?,?,?,?,?)"); 
      // values are prepared to bind
    $stmt = mysqli_prepare($con,$sql);
    mysqli_stmt_bind_param($stmt,"sssss",$_POST['first_name'],$_POST['last_name'], $_POST['phonenumber'], $_POST['guest'], $_POST['event']);
  $stmt->execute();
   if (!$stmt)// Was not updated
   {
       // shows error
           echo("There was an error with your RSVP.  Please try again.");
           mysqli_stmt_close($stmt);
   }
   else //Was updated
   {
           echo("Your RSVP has been completed.");
   }
   //End database connection   
  mysqli_close($con);
   ?>
this is my database file that was provided by my professor
    <?php
    $myHost = "localhost"; // localhost, do not change this string
    $myUserName = "cmorales";   // CHANGE TO YOUR USERNAME
    $myPassword = "";   // CHANGE TO YOUR PASSWORD
    $myDataBaseName = "cmorales_project"; // CHANGE USERNAME 
       username_project
   $con = mysqli_connect( "$myHost", "$myUserName", "$myPassword", 
       "$myDataBaseName" );
   if( !$con ) // == null if creation of connection object failed
     {
  // report the error to the user, then exit program
     die("connection object not created: ".mysqli_error($con));
     }
   if( mysqli_connect_errno() )  // returns false if no error occurred
     {
 // report the error to the user, then exit program
die("Connect failed: ".mysqli_connect_errno()." : ". 
mysqli_connect_error());
   }
  ?>
 
    