Unique identifier link value receiving failure in PHP isset GET - php

Question

I'm trying to verify registration via email with sending of unique identifier link to user.
I use it from remote server. Server, username, password, database values are correct, works fine with other .php-s, only difference verify.php has connection included, instead require 'connection.php';, but I'm not sure if connection produces following failure.
Sends:
$message = "<p>Hello, dear $user</p><a href='https://mypage.info/php/reg/verify.php?vkey=$vkey'>Confirm Account</a>";
and receives on email:
https://mypage.info/php/reg/verify.php?vkey=4bf65cf02210b304143589e6dc3714c0
link to verify.php, but php throws Something went wrong, or
if instead die I'll check echo 'VKey: '. $vkey; or echo $mysqli->error; shows nothing.
Seems like by some reason if (isset($_GET['vkey'])) does not receives vkey correctly. I'm not sure what I'm doing wrong here:
Alert! This example code shows insecure method since accepts SQL parameters directly from user input. Requires Prepared Statements and Bound Parameters, real_escape_string()
<?php
if (isset($_GET['vkey'])) {
$vkey = $_GET['vkey'];
$mysqli = NEW MySQLi ('server','username','password','db');
$resultSet = $mysqli->query("SELECT verified, vkey FROM registration WHERE verified = 0 AND vkey = '$vkey' LIMIT 1");
if ($resultSet->num_rows == 1)
{
$update = $mysqli->query("UPDATE registration SET verified = 1 WHERE vkey = '$vkey' LIMIT 1");
if($update){
echo "Your account has been verified. You may now login.";
} else {
echo $mysqli->error;
}
}
else
{
echo "This account invalid or already verified";
}
} else {
die("Something went wrong");
}
?>

Answer 1

Your code looks in the $_POST array instead of $_GET
if (isset($_GET['vkey'])) {
$vkey = $_GET['vkey'];

Answer 2

SUGGESTION: instrument everything possible, and post back what you find.
For example:
<?php
echo "vkey=" . $_GET['vkey'] . "...<br/>";
if (isset($_GET['vkey'])) {
$vkey = $_GET['vkey'];
echo "vkey=" . $vkey . "...<br/>";
$mysqli = NEW MySQLi ('server','username','password','db');
echo "mysqli: SUCCEEDED...<br/>";
$resultSet = $mysqli->query("SELECT verified, vkey FROM registration WHERE verified = 0 AND vkey = '$vkey' LIMIT 1");
echo "resultSet: SUCCEEDED...<br/>";
echo "resultSet->num_rows=" . $resultSet->num_rows . "...<br/>";
if ($resultSet->num_rows == 1)
{
$update = $mysqli->query("UPDATE registration SET verified = 1 WHERE vkey = '$vkey' LIMIT 1");
echo "update: SUCCEEDED...<br/>");
if($update){
echo "Your account has been verified. You may now login.";
} else {
echo $mysqli->error;
}
}
else
{
echo "This account invalid or already verified";
}
} else {
echo "ERROR STATE: " . $mysqli->error . "...<br/>";
die("Something went wrong");
}
?>
And no, I can't think of "... why md5 string" could be the culprit. But I think the above instrument (or similar) might help us determine EXACTLY where the problem is occurring ... and thus how to resolve it.
'Hope that helps...