This also affects real machines, not only virtual ones. After installing virtualbox-guest-x11:
At first I encountered this bug: https://forums.opensuse.org/showthread.php/518831-The-screen-locker-is-broken-and-unlocking-is-not-possible-anymore I also noticed that "konsole" would not start anymore. After logging out completely, I got the black screen. The same happened after rebooting. Just a black screen, but the virtual terminals worked. I fixed it by simply removing the package: sudo apt purge virtualbox-guest-x11 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1683043 Title: Black screen after installing virtualbox-guest-x11 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/virtualbox-guest-additions/+bug/1683043/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
