Installation of Virtual Box on Mac OS -- Kernel Driver Not loaded

Recently I've upgraded to MacOS (Catalina) 10.15.1 and I've upgraded to VB 6.0.14 and started getting above issue while starting my earlier guestOs i.e. Ubuntu 18.04LTS.

I've tried various solution, but nothing worked except this:

spctl kext-consent add VB5E2TV963

So you need to run this command in recovery mode terminal ONLY (Top Menu Bar » Utilities » Terminal). I was avoiding going into recovery mode but when nothing worked and you don't have any other option; you can save this command and note it down in some mobile app or notepad.

P.S.: In order to open recovery mode, you need to restart your system and press ⌘+R.

Go to Security and Privacy / General in your System Settings. You will see that software from Oracle has been blocked. Allow it, and the software will work. The 'allow Oracle' option only exists for 30mins after the installer error.

See Apple's technical note on this.