The guru meditated on "VERR_INVALID_STATE", meaning that something your guest is trying wasn't compatible with the guest setup. VT-x is working, memory & core count are good, assuming the guest OS doesn't need more. The boot process does not get to accessing anything from the guest OS, though.
You're running the Ubuntu fork of Virtualbox, not the official download from virtualbox.org:
00:00:00.577168 VirtualBox VM 6.0.14_Ubuntu r132055 linux.amd64 (Oct 17 2019 07:24:16) release log
We don't support the forks here. You might want to get the official download.
You have the OSE version and the VNC extension pack installed. Maybe these are broken?
00:00:00.577235 Package type: LINUX_64BITS_GENERIC (OSE)
00:00:00.583139 Installed Extension Packs:
00:00:00.583156 VNC (Version: 6.0.14 r132055; VRDE Module: VBoxVNC)
This is your guest type:
00:00:00.598040 Guest OS type: 'Linux26_64'
What guest OS are you trying to install or run?