Can't drag & drop files from desktop to browser (i.e. Google Drive)

[Brent_Santin]

Hi, I'm using Lubuntu 20.04.6.

Recently (like in the past month) I've notice that I can no longer drag files from the desktop into my browser. When I do so, the mouse pointer just shows a red "NO" symbol (red circle with diagonal line through it).
This happens when I try to drag and drop a file into Google Drive, MicroSoft OneDrive, or attach files to a web-based e-mail I'm composing (i.e. G-mail, Yahoo mail).

I'm not sure what "broke" this functionality.

I've tried clearing my browser cache and rebooting. I've tried Incognito mode (private browsing mode) with no luck.

My web-browser is Firefox.

Does anyone have a clue what is preventing this from working?

Thanks.

[TheFu]

Is firefox a snap package on your system? If so, it runs with forced constraints and only specifically allowed programs are allowed to interface with it. In the snap world, they call them "connections".

That's my guess, but I don't **know** that's the issue. I don't work in that way.

Years ago, most of the major browsers decided that we shouldn't be allowed to open HTML files stored on our desktops. They said it was a security feature to prevent some nasty things, which is probably true. This was before Canoncial decided to start pushing snap packages.

I don't use Lubuntu and I don't know which firefox it has on 20.04. I do run 20.04, but I use Firefox-ESR which comes from a mozilla PPA. This is my way to avoid snaps. Some of my workflows require a few different programs to work together that the snap people never considered. After all, if we wanted to be forced to work in only 1 way, then we'd run MacOS, right?

If you don't have a snap version of firefox installed, then it can't be the snap constraints. It might be a default setting that you'll need to find inside about:config. Google found this: https://kb.mozillazine.org/Links_to_...es_do_not_work

[Brent_Santin]

Okay...I checked and it doesn't appear that my Installation of FireFox is a snap package.

Furthermore, I installed the Chromium web browser, to see if it would have the same problem. The only version available to me was in a Snap package, so I installed it.
Chromium (Snap) does work fine with drag and drop from desktop into browser (tested in Google Drive).

So this appears to be a problem with Firefox, but as I said it only appeared in the past month. I'm not sure what changed!

Does anyone have an idea?

Thanks.

[Brent_Santin]

Update:

I tried:

- Completely uninstalling FireFox, including preferences folder.
- Tried reinstalling via the snap package, and also the non-snap way.
- Tried starting Firefox in Troubleshooting (i.e. safe) mode.

Nothing fixed the issue.

Chromium installed as a Snap package, however, continues to work fine fro drag & drop.

Brent

[currentshaft]

What happens if you try opening the file in Firefox - put "file:///home/" in the address bar and find it.

[Brent_Santin]

What happens if you try opening the file in Firefox - put "file:///home/" in the address bar and find it.

That method works. i.e. If I right click a pdf on my desktop and choose "open with Firefox" it loads up in Firefox.
However, when I try and drag the pdf from my desktop into the Firefox window I get the red circle with a slash through beside my mouse pointer.

Unfortunately, for online services like Google Drive, the only way to upload files is to drag them from the desktop into the browser.

[currentshaft]

Can you open about:support in Firefox and see what it says under Window Protocol?

[Norm24]

I'm running FF installed through Ubuntuzilla ppa and have no issues dragging and dropping files into the browser.I'm using Ubuntu Mate 22.04 but that shouldn't make a difference when it comes to that particular function.

[#&thj^%]

Is any sand-boxing tools in play here? (firejail is one)

Something like this will show us what you have now:

apt policy firefox
firefox:
  Installed: 128.0.3~build1
  Candidate: 128.0.3~build1
  Version table:
     1:1snap1-0ubuntu6 500
        500 http://us.archive.ubuntu.com/ubuntu oracular/main amd64 Packages
 *** 128.0.3~build1 1000
       1000 https://packages.mozilla.org/apt mozilla/main amd64 Packages
        100 /var/lib/dpkg/status

[halogen2]

Okay...I checked and it doesn't appear that my Installation of FireFox is a snap package.

What type of installation is it (deb from Mozilla, deb from mozillateam PPA, tarball downloaded from Mozilla, flatpak,...)?

If I right click a pdf on my desktop and choose "open with Firefox" it loads up in Firefox.

That is not the same as going to file:///home/ in Firefox and clicking within Firefox from there to locate and open the file.

If you've opened the file with right-click > "Open with Firefox" in the current browser session, completely quit Firefox and start it new (not opening the file) before trying this troubleshooting test.