Mpdf 7 class /mpdf/mpdf() not found setalah di hosting

Kenapa setelah saya hosting aplikasi ke web, mpdf nya jadi error gini ya suhu? padahal kalau di localhost lancar2 saja. apa yang mesti saya perbaiki? Saya pakai framework codeigniter.

Type: Error

Message: Class 'mpdf\mpdf' not found

Filename: /storage/ssd3/097/12529097/public_html/application/controllers/Cetak.php

Line Number: 27

controller : $mpdf = new \Mpdf\Mpdf([ 'default_font_size' => 12, 'default_font' => 'DejaVuSans' ]);

config: $config['composer_autoload'] = 'assets\vendor\mpdf\autoload.php';