Ubuntu 18.04 no GUI !!!

Upgraded 16.04 (Xenial Xerus) release to 18.04 (Bionic Beaver) - Post installation machine booted without GUI under multi-user target!!! Solution below -

• Installation: Ubuntu 16.04 (Xenial Xerus)
• Upgraded release: Ubuntu 18.04 (Bionic Beaver)
• No GUI after upgrade machine drops to CLI
  
• Tried to start X
• Using command: $ startx
• This worked (Not permanent solution)
• Tried to configure lightdm and gdm
• Using command: $ sudo dpkg-reconfigure gdm, $ sudo dpkg-reconfigure lightdm
• Found that 'gdm' and 'lightdm' was not installed post upgrade and thus CLI was being shown on every boot
• Installed gdm 
• Using command: $ sudo apt-get install gdm

Choosing lightdm over gdm

• Installation: Ubuntu 12.04 Precise.
  
• Default Display Manager installed: lightdm
  
• Changed Display Manager to: gdm
• Using command: $ sudo apt-get install gdm
• Selected default display manager as 'gdm' when prompted.
  
• Switch back to: lightdm
• Using command: $ sudo dpkg-reconfigure gdm
• Selected option: lightdm

Switched Back to lightdm because:

• PC boots faster.
• Ubuntu loads faster.
• Performance improvement.