Why is password hash not updating.... Mysqli Prepared Statement - php

Question

I have a little bit of a problem with a password hash not being updated in a database and I'm struggling to see what I've done wrong. If anyone could help it would be much appreciated.
Basically I have a login.php script, which used to just employ md5 and salt to a user's password and store it in a mysql db, which I know is out of date. So I've recently tried to update it to update users passwords to PHP password_hash when they next log in.
I first collect the password via post then call the db to compare it to the hash in the db. If the password verifies I then run the db password through password_needs_rehash to check if it needs rehashing. If it does then it'll generate a new has and store this to a variable to be run through a mysqli prepared statement that updates the hash along with the time they've last logged in, otherwise it'll just update the db with the last login.
It seems to fail to update the new hash (even though I've checked it is generated) but still updates the time in the query. There are no emails coming through from the exception code or any php errors to report.
// Check if a newer hashing algorithm is available or if the cost has changed
if (password_needs_rehash($dbpass, PASSWORD_DEFAULT, $cost)) {
// If so, create a new hash, and replace the old one
$newHash = password_hash($password, PASSWORD_DEFAULT, $cost);
}
//update last login date
date_default_timezone_set("Europe/London");
$servertime = date("Y-m-d H:i:s");
// connect to db for mysqli
require('../dbconn/user.php');
// query to update password, increment number of logins and set last login date for user
$update_pass_stmt = $mysqli->stmt_init();
// if new hash has been generated
if (isset($newHash)) {
$q = "UPDATE users SET theirpassword=?, lastlogin=? WHERE email=? LIMIT 1";
if ($update_pass_stmt->prepare($q)) {
$update_pass_stmt->bind_param('sss', $newHash, $servertime, $email);
$update_pass_stmt->execute();
$update_pass_stmt->close();
}
} else {
$q = "UPDATE users SET lastlogin=? WHERE email=? LIMIT 1";
if ($update_pass_stmt->prepare($q)) {
$update_pass_stmt->bind_param('ss', $servertime, $email);
$update_pass_stmt->execute();
$update_pass_stmt->close();
}
}
if ($mysqli->error) {
try {
throw new Exception("MySQL error $mysqli->error <br> Query:<br> $q", $mysqli->errno);
} catch(Exception $e) {
$mess = "Error No: ".$e->getCode(). " - ". $e->getMessage() . "<br >";
$mess .= nl2br($e->getTraceAsString());
$contact_email = "webmaster#example.co.uk";
$message_sub = "Mysqli Login Query Error [EN-UUTIME01]";
$hdrs = "From: " . $contact_email . "\r\n";
$hdrs .= "Reply-To: ". $contact_email . "\r\n";
$hdrs .= "MIME-Version: 1.0\r\n";
$hdrs .= "Content-Type: text/html; charset=UTF-8\r\n";
mail($contact_email, $message_sub, $mess, $hdrs);
}
$mysqli->close();
$_SESSION['internalerror'] = TRUE;
header("Location: ". $MM_redirectLoginFailed );
exit();
}
$mysqli->close();
I've echoed out in each section of the code and it seems to be running through to the correct sql statement.
I can only think I've either missed an obvious typo or I've got my logic wrong somewhere.
Any help always appreciated, thank you.

Answer 1

Well as embarassing as it may be, I found the solution to my issue. The email variable I was passing into the query was empty. I'd named it differently earlier on in my code!
Although, why I didn't get a query error email or log anywhere I'm not sure still... see my comment with #RyanVincent above.
Thanks all for taking the time to look over the code!