I have the same problem in Odoo V13 Enterprise. In production server i use Nginx proxy, but in test server I don't use Nginx and the problem is the same. I could not download or view pdf file > 17MB.

Edit: set nginx proxy-buffering on work for me in test server, but the error still remains in my production server.

Hi Marcin:

If you have a reverse proxy server running in front of the Odoo instance, check the configuration of the reverse proxy to see if it is limiting the download file size.