Not all servers run the latest version of PHP or have enabled all the packages. This small replacement saved me a lot of frustration with my web host.

mysqli-fix.php

<?php
// Replace
$data = $query->fetch_all(MYSQLI_ASSOC);

// With
$rows = [];
while ( $row = mysqli_fetch_assoc($query) ) {
    $rows[] = $row;
}
$data = $rows;

// Or Even, Define
function fetch_assoc($query) {
    $rows = [];
    while ( $row = mysqli_fetch_assoc($query) ) {
        $rows[] = $row;
    }
    return $rows;
}

// And Use
$data = fetch_assoc($query);