app/check_setup.php

<?php

// PHP 7.4.0 minimum
if (version_compare(PHP_VERSION, '7.4.0', '<')) {
    throw new Exception('This software requires PHP 7.4.0 minimum');
}

// Check data folder if sqlite
if (DB_DRIVER === 'sqlite' && !is_writable(dirname(DB_FILENAME))) {
    throw new Exception('The directory "' . dirname(DB_FILENAME) . '" must be writeable by your web server user');
}

// Check PDO extensions
if (DB_DRIVER === 'sqlite' && !extension_loaded('pdo_sqlite')) {
    throw new Exception('PHP extension required: "pdo_sqlite"');
}

if (DB_DRIVER === 'mysql' && !extension_loaded('pdo_mysql')) {
    throw new Exception('PHP extension required: "pdo_mysql"');
}

if (DB_DRIVER === 'postgres' && !extension_loaded('pdo_pgsql')) {
    throw new Exception('PHP extension required: "pdo_pgsql"');
}

if (DB_DRIVER === 'odbc' && !extension_loaded('pdo_odbc')) {
    throw new Exception('PHP extension required: "pdo_odbc"');
}

if (DB_DRIVER === 'dblib' && !extension_loaded('pdo_dblib')) {
    throw new Exception('PHP extension required: "pdo_dblib"');
}

// Check other extensions
foreach (array('gd', 'mbstring', 'hash', 'openssl', 'json', 'hash', 'ctype', 'filter', 'session', 'dom', 'filter', 'SimpleXML', 'xml') as $ext) {
    if (!extension_loaded($ext)) {
        throw new Exception('This PHP extension is required: "' . $ext . '"');
    }
}

// Fix wrong value for arg_separator.output, used by the function http_build_query()
if (ini_get('arg_separator.output') === '&amp;') {
    ini_set('arg_separator.output', '&');
}