Check the permissions on the directory you are trying to download/write the files to. More then likely Firefox does not have the correct permissions to write to that directory.

So you will have to look at a Chmod guide for your Linux distro to give Firefox read & write access to that location.

I don't get as far as being offered a directory to save to. If I select to use the standard download directory, it downloads it. If I go back to "ask you where to save files" clicking the same link does nothing.

The directories I am trying to use I use are on a local server. They include my standard Download directory which works fine. I use them to regularly to edit files regularly using other software .. text editor, LibreOffice, Thunderbird etc. and have no problems with permiossions.

Is there some obscure file somewhere which could contain an error message being generated?

Still can be a permission problem, happens often enough as Firefox was not installed in the same group permission as your other programs. You can run it in root to see if that makes a difference.

You can refresh by going into your "about:support" and clicking "refresh firefox"

After that make sure your "Compositing" is set to "OpenGL" in your "about:support" screen. If it's set on basic, then goto your "about:config" and find the key layers.acceleration.force-enabled and set it to true and restart. Usually Compositing is set to Basic on Linux, which makes FF run like ass.

It Worked. The problem was somewhere in my profile but the "Refresh" button fixed it.

Thank you for the tip about "about:support". I've not seen it before. When I first clicked the "Refresh" button I was put off by the warnings about losing my set up and information that I had built up over the years. This is what I did:

• Moved my profile so that Firefox would create a clean one.
• Restarted Firefox, download now worked.
• Ran the "Refresh" routine, download still worked.
• Closed FF, replaced the clean profile with my original and restarted. download stopped working again.
• Ran the refresh" routine with my old profile still present. Download now worked again. I still had all my bookmarks, saved passwords and other stuff I wouldn't have wanted to lose. It lost some of my settings and the Add-Ons but it only took ten minutes to put that right. My Add-Ons are being reviewed anyway because of the impending changes in FF.

I had to delete a very long standing profile in LibreOffice so I was impressed that the "refresh" button was able to fix it without requiring me to recreate it.

I would love to know what in the profile was causing the problem but I'd already used about:config to reset the download settings and remove file entries with invalid paths. After that I was stuck until I got your suggestion.