link to page with $_SERVER REQUEST_METHOD 'GET' does not load - php

Question

I have a verification link like this:
http://nailsalon.gwiddle.co.uk/nailsalon/verify.php?email=email#enail.com&hash=66808e327dc79d135ba18e051673d906.
When I click it or manually insert it to the address bar I get error 500 or File not found. The page which I am trying to access through this link uses the $_GET array.
When I use a link like this:
http://nailsalon.gwiddle.co.uk/nailsalon/index.php?id=1 which leads to a page which doesn't use the $_GET it loads without problem.
There is another question with the same problem but no solution here:
Internal server error on email verification
Here is the code of the target page:
if(isset($_GET['email']) && !empty($_GET['email']) AND isset($_GET['hash']) && !empty($_GET['hash'])){
$email = clear_entry($_GET['email']);
$hash = clear_entry($_GET['hash']);
/*Query that retrieves all users with the given email and hash*/
$result = $mysqli->query("SELECT * FROM users WHERE user_email='$email' AND hash='$hash' AND is_activated='0'");
/*Checks if the account is already verified*/
if ($result->num_rows == 0 ){
$_SESSION['message'] = "Account has already been activated or the URL is invalid!";
header("location: error.php");
}else{
$_SESSION['message'] = "Your account has been successfully activated!";
$mysqli->query("UPDATE users SET is_activated='1' WHERE user_email='$email'") or die($mysqli->error);
$_SESSION['active'] = 1;
header("location: success.php");
}
}else{
$_SESSION['message'] = "Invalid parameters provided for account verification!";
echo "Invalid parameters provided for account verification!";
header("location: error.php");
}
?>