Since 31/01/22 all the download files become corrupted.

Solved!

Just comment out the lines in the controller responsible for set the header "Content-Length" and then set the header  "Transfer-Encoding: chunked".

File: app/code/core/Mage/Downloadable/controllers/DownloadController.php

on _processDownload method on line 73 comment out these lines and add this other:

...
protected function _processDownload($resource, $resourceType)
        ....

        // if ($fileSize = $helper->getFilesize()) {
        //     $this->getResponse()
        //         ->setHeader('Content-Length', $fileSize);
        // }

        $this->getResponse()
        ->setHeader('Transfer-Encoding', 'chunked');

        ....
        }

Now it works but could you please tell me if there are some other headers to add or remove?

Thanks for following up. I'm glad to hear you got this working. I can't provide guidance on what other headers you should or shouldn't be setting though, as that depends on how the app works and what the app does.

Sure, I understand. However, did you guys change just that recently?

Yes, that update was deployed towards the end of January.

Thanks for your support.

Update: in order to temporarily accommodate clients that don’t properly support automatically handling “Transfer-Encoding: chunked”, we’re temporarily rolling back this change, so that these links will no longer use “Transfer-Encoding: chunked” and will instead return “Content-Length” on HTTP/1.1. We will begin rolling that out starting around 2/17. That will be in place until around 3/1. At that point, we will begin using “Transfer-Encoding: chunked” and no longer returning “Content-Length” on HTTP/1.1 again.

Going forward, please ensure that your clients are able to automatically handle both chunked encoding and non-chunked encoding automatically.

Then I'll set it like this:

if ($fileSize = $helper->getFilesize()) {
    $this->getResponse()->setHeader('Content-Length', $fileSize);
} else {
    $this->getResponse()->setHeader('Transfer-Encoding', 'chunked');
}

Update: the team has been able to complete some further updates to our infrastructure to be able to support the previous non-chunked behavior going forward indefinitely. That means that we plan to continue returning Content-Length (and not 'Transfer-Encoding: chunked') in the future and will not be reverting this as previously planned. (Regardless, for HTTP compatibility in general, we still recommend you make sure your HTTP clients support both types.) Hope this helps!

I noticed, since around September/October 2023, downloads really often (8 in 10 times) are interrupted at different size. And just now I remembered this issue.

Did you change something again?

I also opened this thread.

kamzata I moved your message to its own thread here: https://www.dropboxforum.com/t5/Dropbox-API-Support-Feedback/Re-Since-31-01-22-all-the-download-files-become-corrupted/td-p/754307

Please follow up there with the details so we can look into the current issue for you.