JDownloads 4.0.26, Joomla 4.2.8, PHP 8.0.28, standard backend and frontend template, new Joomla installation

I ran into a very curious problem. I have a site with flight simulator add-ons (fsaddons.fi), and it is working very well for uploads and downloads. Yesterday the newest and biggest add-on (EFFO) was uploaded to the site (using FTP as some server restriction caused a 413 error when trying upload in JDownloads). The file is about 900MB in size. Everything fine so far, the file shows normally among the downloads. The file size is correct. But when downloading the file it is always cut at 512MB and broken when you try to unzip it! This is not a restriction from the server side, as it downloads nicely from an html file with a directlink to the file (tried this in a separate directory and this is now used as a workaround). All upload size definitions - in JDownloads configuration, in .htaccess and php.ini, (checked in CPanel and manually in the files) are set to 1024MB.

Is there a download size restriction in JDownloads, or could there be something like that in Joomla?

Hi,
Actually, such limits do not exist in jDownloads unless they are set by the user.
But I'm going to do some tests with large files on different installations right away.
I'll get back to you.

Hi,
I have created a new category on the official jDownloads demo installation:
https://jd40.jdownloads.org/downloads/category/62-test-files-of-different-sizes
There you can now find downloads with files between 100 MB and 5 GB. I was able to download all files to my PC without any problems. Please try it yourself.

This means that further tests are actually unnecessary and the problem should be somewhere with your hoster. The fact that you can download the file directly (without using a PHP script) does not necessarily mean that there is a bug in jDownloads. It is probably due to restrictions (time limits etc.) when using PHP scripts. I am not a server expert, so I can hardly help you in this respect.

By the way, you can create test files of any size here: https://testfiledownload.com/test-file-generator/

Thanks for trying it out! Then that possible reason is ruled out and I will have to dig into the php or server settings. I will contact the support at the webhotel...

You could use for the moment also this option, see pic.

Tried that, but then no downloads work - I get a 403 error on all downloads when the PHP script is inactivated. Probably stiff settings in my htaccess to avoid direct linking...

Still trying to figure out what causes tis. The webhotel support has looked into it and not found any restrictions. They increased the PHP timeout values, but tht did not help. Today I found this discussion: https://stackoverflow.com/questions/2320351/is-there-some-limit-on-a-size-of-a-file-when-causing-a-download-with-php

It made me look at what resources I have available at the webhotel. Turned out that the physical memory limit is 512 Mb!  Then I tried to download the file and monitored the memory usage. During the download it it used more than 99.5% physical memory. When downloading the same file using the direct html link the physical memory usage never exceeds 50%.

So my question is - is the file entirely read into the physical memory before it is transmitted? That would explain the 512 Mb cutoff. I am not a server expert and do not know how this download process works so this is just guesswork...