Clipboard sharing not working in Virtualbox with Ubuntu guest OS

If this happens, make sure clipboard sharing is enabled in the guest settings.

If it still doesn’t work, re-insert the VBox Additions ISO to the guest OS and reinstall VBox Additions, reboot guest OS and try again.

It may work for a while until eventually breaking again if Virtualbox is updated. After upgrading Virtualbox, usually there will be a new version of VBox Additions.