1685250 - Unable to download custom extension file

Status: RESOLVED DUPLICATE of bug 1684183

(Firefox :: File Handling, defect)

Description

[Satoshi Ookami]

Attachment: Pre-84.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36

Steps to reproduce:

The application we are developing uses a custom extension file (visible on Pre-84.png image) that can be downloaded.
However, ever since one of our customers updated to Firefox 84, the custom extensions started being replaced by a zip extension.
The application requires the custom extension for correct use and therefore, our customers that are using Firefox are unable to use the feature the custom extension provides.

This behavior is only observed on the latest Firefox version, other browsers and older Firefox versions do not have this behavior as can be seen on this Stack Overflow thread.
https://stackoverflow.com/questions/65398445/firefox-84-0-is-changing-custom-file-extension-from-downloaded-file

Actual results:

Instead of download a .bcki file, Firefox downloads a .zip file.

Expected results:

Firefox should have downloaded the custom extension file without any changes.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.