Let me add a "research" bump to this - the black screen also happens if you're trying to use the built-in Desktop Sharing functionality in 16.04.1 as well, and (at any point) you switch user accounts.
It seems to really boil down to switching user accounts and the lock screen; it's not just an x11vnc issue but again also happens to a stock/up to date 16.04.1 machine even with just 1 user account after enabling Desktop Sharing. Here's how to reproduce: 1) Enable Desktop Sharing, options don't really matter here. (You can give view-only, or you can allow control.) Confirming access, password, none of this matters. 1a) If you're connecting from a Windows machine using TightVNC Viewer, RealVNC Viewer, or UltraVNC Viewer, you'll have to disable encryption on the Ubuntu host. Simplest way to do this is pull up Terminal (admin/root not required) and execute: gsettings set org.gnome.Vino require-encryption false Otherwise your Windows client will not understand the encryption and fail to connect. (See also: http://ubuntuhandbook.org/index.php/2016/07/remote-access-ubuntu-16-04/) 2) Connect to the Ubuntu [shared] host; I've used both RealVNC Viewer and UltraVNC Viewer. 3) After connecting and having the Ubuntu host in a VNC connection window, with control (or at the Ubuntu host keyboard), switch to the 'Guest Session' user. [You don't even need more than 1 user on the machine, just switch to a Guest Session.] 4) Your VNC window will now either still show the user's desktop (as it was) but it will be static and you will not be able to manipulate it * OR * Your VNC window will now be a black, blank screen. Your Ubuntu host, however, will be at the Guest Session user screen. Whether you disconnect and re-connect with your VNC application, it does not matter. You still have a static or black screen you cannot do anything with. 5) Log out of the Guest Session, which will return you to the lock screen where you can enter your user account's password. If you connect prior to logging in with your VNC client, you'll still have a static/black screen. However, after you type the user password to re-log in to the desktop at the Ubuntu host, you will be able to control (or view) from the VNC guest again. I was hoping to use Desktop Sharing in lieu of using a different VNC Server in 16.04.1, however, that will obviously not work. I have also tested this in Ubuntu MATE 16.04.1 and found all the above is still true. Maybe I'm spoiled in Windows world, using UltraVNC Server on my Win7 boxes and being able to switch from user account to user account with no issues (other than a slight delay while the Windows login/user switch screen comes up and goes away). Maybe this is something out of spec for what Ubuntu is capable of. I just wanted to share this in the hopes that a fix is finally found, since again, this is NOT only related to x11vnc as I think people initially thought. In that regard, if I need to post a new thread for this bug somewhere else, or my post needs to be moved accordingly, feel free to do so. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1287171 Title: light-locker breaks x11vnc as service To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/light-locker/+bug/1287171/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
