Failed to install VirtualBox additions

That problem could be solved like this

sudo apt-get install dkms build-essential make gcc automake libssl-dev linux-headers-generic autoconf checkinstall intltool libtool module-assistant perl python python3
sudo reboot

After this install VirtualBox additions as usual.

Expand Partition, Split VMDK to Multiple Files on VirtualBox

Expand Partition

C:\Windows\system32>cd C:/Program Files/Oracle

C:\Program Files\Oracle>cd VirtualBox

C:\Program Files\Oracle\VirtualBox>VBoxManage modifyhd "c:\Users\user_name\VirtualBox VMs\Windows7\Windows7-disk1.vmdk" --resize 20000
0%...
Progress state: VBOX_E_NOT_SUPPORTED
VBoxManage.exe: error: Resize hard disk operation for this format is not impleme
nted yet!

C:\Program Files\Oracle\VirtualBox>VBoxManage clonehd "c:\Users\user_name\VirtualBox VMs\Windows7\Windows7-disk1.vmdk" "c:\Users\user_name\VirtualBox VMs\Windows7\Windows7-disk1.vdi" --format VDI --variant standard
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Clone hard disk created in format 'VDI'. UUID: fa9fd259-fe7b-4a84-90c2-e7e0a516c
5ad

C:\Program Files\Oracle\VirtualBox>VBoxManage modifyhd "c:\Users\user_name\VirtualBox VMs\Windows7\Windows7-disk1.vdi" --resize 20000
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

C:\Program Files\Oracle\VirtualBox>


Now you can expand partition in gparted. Right click on partition -> resize

Split VMDK Volume to multiple parts

C:\Program Files\Oracle\VirtualBox>VBoxManage.exe 
clonehd "c:\Users\UserName\VirtualBox VMs\Ubuntu\Ubuntu-disk1.vmdk" 
"c:\Users\UserName\VirtualBox VMs\Ubuntu\Ubuntu-frags.vmdk" 
--format VMDK 
--variant Split2G
0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Clone medium created in format 'VMDK'. UUID: bc391000