Form submission, php, keep getting error message in array - php

Question

I'm working on a forum for a school project (high school) and I have a register form. Everything works but when I submit the form I get my set error that says "An error has occurred". I'm not getting any MYSQL errors and am wondering what's wrong with my code. Please note, everything should be working but for some reason it does not submit to the database. I know the html is good so I'm only submitting the php.
register.php
<?php
//get required files
include 'inc/config.php';
//get all variables to avoid errors
$firstname = ""; //first name of user
$lastname = ""; //last name of user
$username = ""; //username of user
$email = ""; //email of user
$city = ""; //current city
$password = ""; //password
$password2 = ""; //confirm password
$date = ""; //signup date
$error_array = array(); //holds all error messages
$ip = ""; //ip address of user
$allowed_cities = array("Toronto","Ottawa","Hamilton","London","Windsor","Kingston"); //holds all cities allowed
$profilepic = ""; //profile photo
$code = ""; //email token to verify account
//Profile Photo Settings
$allowed_filetypes = array('.jpg','.gif','.bmp','.png'); // These will be the types of file that will pass the validation
$max_filesize = 9999999999; // Maximum filesize in BYTES - SET IN to a low number for small files
$upload_path = 'data/profilepictures/'; // The place the files will be uploaded to (currently a 'profile pictures' directory)
if(isset($_POST['submit'])){
//First Name
$firstname = strip_tags($_POST['firstname']); //Remove html tags
$firstname = str_replace(' ', '', $firstname); //remove spaces
$firstname = ucfirst(strtolower($firstname)); //Uppercase first letter
//Last Name
$lastname = strip_tags($_POST['lastname']); //Remove html tags
$lastname = str_replace(' ', '', $lastname); //remove spaces
$lastname = ucfirst(strtolower($lastname)); //Uppercase first letter
//Username
$username = strip_tags($_POST['username']); //Remove html tags
$username = str_replace(' ', '_', $username); //remove spaces and put a underscore
//Note: preg match for username done later
//Email
$email = strip_tags($_POST['email']); //Remove html tags
$email = str_replace(' ', '', $email); //remove spaces
//City
$city = strip_tags($_POST['city']); //Remove html tags
$city = str_replace(' ', '', $city); //remove spaces
$city = ucfirst(strtolower($city)); //Uppercase first letter
//Password and Confirm Password
$password = strip_tags($_POST['password']); //Remove html tags
$password2 = strip_tags($_POST['password2']); //Remove html tags
//Profile Picture
$profilepic = $_FILES['photo']['name']; // Get the name of the file (including file extension)
$ext = substr($profilepic, strpos($profilepic,'.'), strlen($profilepic)-1); // Get the extension from the profilepic
//Email Verification
$code=substr(md5(mt_rand()),0,15); //token to verify email
//Date and IP Address
$date = date("Y-m-d"); //Current date
$ip = $_SERVER['REMOTE_ADDR']; //IP Address
//Check submissions for errors
//Check Firstname
if(strlen($firstname) > 25 || strlen($firstname) < 2) {
array_push($error_array, "Your first name must be between 2 and 25 characters<br>");
}
//Check Lastname
if(strlen($lastname) > 25 || strlen($lastname) < 2){
array_push($error_array, "Your last name must be between 2 and 25 characters<br>");
}
//Check Username
$u_check = mysqli_query($con, "SELECT username FROM users WHERE username='$username'");
$num_rows = mysqli_num_rows($u_check);
if($num_rows > 0) {
array_push($error_array, "Username is taken<br>");
}
if(strlen($username) > 30 || strlen($username) < 3){
array($error_array, "Your username must be between 3 and 30 characters<br>");
}
if(preg_match('/^[a-z0-9]{6,10}$/', $username)) {
array_push($error_array, "Your username includes invalid characters<br>");
}
//Check Email
$e_check = mysqli_query($con, "SELECT email FROM users WHERE email='$email'");
$num_rows2 = mysqli_num_rows($e_check);
if($num_rows2 > 0){
array_push($error_array, "Email already in use<br>");
}
$allowed_emails = array('student.tdsb.on.ca', 'delasalle.ca', 'ucc.on.ca');
$explodedEmail = explode('#', $email);
$domain = array_pop($explodedEmail);
if ( ! in_array($domain, $allowed_emails))
{
array_push($error_array, "Your student email is not allowed<br>");
}
//Check City
if (!in_array($city, $allowed_cities)) {
array_push($error_array, "Our service is not available in your city<br>");
}
//Check Passwords
if($password != $password2) {
array_push($error_array, "Your passwords do not match<br>");
}
if(strlen($password > 30 || strlen($password) < 5)) {
array_push($error_array, "Your password must be betwen 5 and 30 characters<br>");
}
if(preg_match('/[^A-Za-z0-9]/', $password)) {
array_push($error_array, "Your password can only contain english characters or numbers<br>");
}
//Check Profile Picture
if(!in_array($ext,$allowed_filetypes)){
array_push($error_array, "The file you attempted to upload is not allowed<br>");
}
if(filesize($_FILES['photo']['tmp_name']) > $max_filesize){
array_push($error_array, "The file you attempted to upload is too large<br>");
}
if(!is_writable($upload_path)){
array_push($error_array, "You cannot upload to the specified directory, please CHMOD it to 777<br>");
}
if(move_uploaded_file($_FILES['photo']['tmp_name'],$upload_path . $profilepic)){
}
else{
array_push ($error_array, "There was an error during the file upload. Please try again later<br>");
}
//Process Data
if(empty($error_array)) {
$password = md5($password); //Encrypt password before sending to database
$query = mysqli_query($con, "INSERT INTO users (firstname,lastname,email,username,password,signup_date,city,profilephoto,email_verified ) VALUES ('$firstname','$lastname','$email','$username','$password','$date','$profilepic','0') ");
array_push($error_array, "Your acccount has been created. Please check your inbox to verify your account<br>");
}
else{
array_push($error_array, "An error has occured. Please try again later<br>");
}
}
?>