Dropbox system tray icon missing, not working

Solution 1:

Unfortunately, most of the answers here are pure voodoo and do not address the actual underlying issues, of which there are two (I'm writing this in part so that I don't forget it myself the next time I'm dealing with this).

Issue number one: Dropbox attempts to fit to whatever environment it runs under, so it does some autodetection work. It sometimes fails, as it's not been updated since 2015. This issue has been addressed by an updated /usr/bin/dropbox wrapper as shipped in Ubuntu's nautilus-dropbox package. So if you want to avoid part of the issues, use it, not the package Dropbox provides. If not, make sure XDG_CURRENT_DESKTOP is set to Unity before Dropbox runs; the Ubuntu version of the package does this internally.

Issue number two: Dropbox is written using Qt, more precisely Qt5. Unity is based mostly on GTK+. Qt can use GTK+ styles, but the implementation has changed significantly in the recent year or so. Unfortunately, the default install of Ubuntu doesn't make it easy to use GTK+ styles from Qt, since QT_STYLE_OVERRIDE is by default set to gtk, which doesn't work as expected, and GTK+ styling fails to initialise, which leads to unavailability of everything based on GTK+ including the D-Bus menu interface, which is what makes the indicator work. Unsetting QT_STYLE_OVERRIDE or setting it to a valid value unbreaks Dropbox and makes the indicator appear again.

Update: Actually, it’s not an Ubuntu default, but something else may be setting the variable to a wrong value — in my case, it was ~/.xsession where I’ve put it some years ago and forgot about it. In any case, it is worth checking and possibly force-setting it to the correct value.

Solution 2:

Lubuntu 14.04 ....I have a few machines, all the same OS. One by one Dropbox icon dissappeared.

I have struggled for months. Couldn't recover icon. Got it now!

1. In terminal type ... dropbox stop && dbus-launch dropbox start
2. Follow the prompts, if any. Two of my machines responded "Dropbox not installed".
3. sudo apt-get install dropbox
4. Repeat line 1. Icon appeared. Didn't stay after re-boot.
5. Repeat line 1, to get icon.
6. Go to Preferences ...General, (Dropbox icon) and un-tick 'Start Dropbox on system startup'.
7. Now to 'Default applications for LXSession' (menu ...Preferences)
8. Under Autostart, un-tick any previous Dropbox attempts (these can be deleted later).
9. Add dbus-launch dropbox start
10. Re-boot.

Solution 3:

There are some workarounds until the bug is fixed. The best one at this moment (working for Linux distros such as Xubuntu, Linux Mint, etc.) is:

dropbox stop && DBUS_SESSION_BUS_ADDRESS="" dropbox start

More details at another StackExchange site: Dropbox icon is not working Xubuntu 14.04 LTS 64 - Ask Ubuntu

Update:

And a more recent workaround that works for more Linux operating systems:

dropbox stop && dbus-launch dropbox start

Solution 4:

The solution for Lubuntu 17.04 is (assuming that you have downloaded a .deb file):

1) Make a copy of Dropbox autostart file:
cp ~/.config/autostart/dropbox.desktop ~/.config/autostart/newstart_dropbox.desktop

2) Edit the file newstart_dropbox.desktop. Change the Exec= line to

Exec=dbus-launch dropbox start -i;

3) Copy the file in /usr/share/applications/dropbox.desktop to ~/.local/share/applications/:

cp /usr/share/applications/dropbox.desktop ~/.local/share/applications/

4)Edit the file that you copied to ~/.local/share/applications/ like you did in step 2. Change the Exec= line to

Exec=dbus-launch dropbox start -i

5) Disable Dropbox autostart, with the following command on terminal:

dropbox autostart n

Thanks for Andrew and the Wepup8 team for the tips.
http://www.webupd8.org/2016/06/fix-dropbox-indicator-icon-and-menu-not.html