I am using Ubuntu 18.04.3 as a guest on VirtualBox. But there was an error during the
make for the 5.1 kernel update. I had this code of error
Building the main Guest Additions 6.0.12 module for kernel 5.1.0. Error building the module. Build output follows.
Then I uninstalled the guest additions from / opt and then reinstalled. He installed without error displayed. But I still can not go full screen. What to do?
Some parts also work: I can copy and paste both ways.