Can no longer use Screen Share to connect Mac to Ubuntu since upgrading to 14.04

Sorted.

Using a combination of clues from http://discourse.ubuntu.com/t/remote-desktop-sharing-in-ubuntu-14-04/1640 (which is all about VNC access) and https://bugs.launchpad.net/ubuntu/+source/vino/+bug/1281250 (which discusses the bug introduced into Vino) I have managed to resolve the matter.

Essentially you have to disable encryption on remote desktop access in Gnome due to a bug that has come to surface in Vino. However some threads tell you uncheck it in the wrong place. Follow these guidelines and you should be able to resolve it quickly.

Specifically it's

dconf > org > gnome > desktop > remote-access > require-encryption - uncheck

and NOT

dconf > desktop > gnome > remote-access > enabled - uncheck

Here is how you do it:

1. First make sure Desktop Sharing is set up properly.
2. Download dconf-tools by typing in Terminal sudo apt-get install dconf-tools
3. Run dconf-editor
4. Expand org
5. Expand gnome
6. Expand desktop
7. Select remote-access
8. Uncheck require-encryption (don't click on Set to Default as it rechecks it)
9. Exit dconf-editor

It should now work. Tested through a reboot and all good.

Hope it helps.

(I have got a screen shot of dconf but don't have enough points on here to post it - I am sure everyone can work it out for themselves though! :-) )

From Raffi's comment and LinuxConfig.org. Tested on Ubuntu 18.04 and 20.04.

$ gsettings set org.gnome.Vino require-encryption false

then verify the setting with

$ gsettings list-recursively org.gnome.Vino | grep encrypt

See also How to set up Vino password via command line