Please explain the problem in detail. What happens? What are the exact error messages?

Go to the Mozilla Add-ons Web Page {web Link} (There’s a lot of good stuff here) and search for a download manager.

This download manager works separately from the browser. The browser tells it what to download, and off it goes.

http://www.freedownloadmanager.org It is a powerful modern download accelerator and organizer for Windows and Mac.

Hello, try reset download actions for all file types: To reset how all file types are handled by Firefox back to default: 1. Open your profile folder:

• Click the menu button , click Help, and select More Troubleshooting Information. The Troubleshooting Information tab will open.
• Under the Application Basics section next to Profile Folder, click Open Folder. Your profile folder will open.

2. Click the Firefox menu and select Exit. 3. Delete or rename the handlers.json file (for example, rename it handlers.json.old). 4. Restart Firefox. For more possible solutions to other problems related to downloading files, go to What to do if you can't download or save files

It is possible that (anti-virus) security software is causing the problem. Try to disable security software temporarily to see if that makes a difference.

Boot the computer in Windows Safe Mode with network support to see if that has effect.

• https://www.bleepingcomputer.com/tuto.../how-to-start-windows-in-safe-mode/
• https://www.digitalcitizen.life/4-ways-boot-safe-mode-windows-10/