mPDF only getting "Finished" when progressBar enabled - php

Question

I'm generating a very large pdf file on my PHP application. The document can reach over 300 pages. The build process may take more than 40 seconds, that's why I want to show the user a message to understand that the file is being generated.
The problem is that when i set $this->progressBar = 1; on config.php file, the progress shows perfect, but when the proces finish, I'm only getting a Finished message, and i'm not redirected to the file.
Heres' my code:
<?php
ob_start();
include('include/mpdf/mpdf.php');
define('_MPDF_URI','../');
$mpdf = new mPDF('','A4', 9, 'freesans', 10, 10, 20, 15, 5, 5, 'L');
$mpdf->SetHTMLHeader($cabecera);
$mpdf->setFooter("Pagina {PAGENO} de {nb}");
$html=utf8_encode($html);
$mpdf->WriteHTML($html);
$mpdf->Output();
ob_end_flush();
I believe someone already has gone through this problem. Please guide me on how I can solve this problem.
Thank you,

Answer 1

The documentation has a note:
Note: You may need to define the constant _MPDF_URI if you use progress bars. The constant _MPDF_URI is needed to redirect the user
to the PDF file (and prior to mPDF 5.0 to locate a javascript file
within the progress bar script). It must be either a relative path
(e.g. '../') or a full URI (e.g. 'http://www.example.com/mpdf/'). If
you do not define it before calling mPDF() mPDF will assign it the
same value as _MPDF_PATH. This is fine if you have used a relative
path. _MPDF_PATH requires either a relative path or a filesystem real
path (e.g. '/homepages/27/d84233457/htdocs/')
Then make sure the ->Output() function has the correct parameters, such as:
$mpdf->Output('yourFileName.pdf', 'I');
For more info see this stack answer.