Ubuntu 18 guest crashes after updating GA from 5.2.22 to 6.1.10

[I excrete rainbows daily]

Host: Ubuntu 18.04
Guest: Ubuntu 18.04

I upgraded VB from 5.2.22 to 6.1.10 and noticed that the bidirectional clipboard could only copy a very small amount of text from host -> guest (but not vice versa). Anything longer than ~500 chars would produce no result. I'm not 100% sure that wasn't the case prior to the VB upgrade, but I'm pretty sure I would've noticed. Since the GA version no longer matched the VB version I thought that might be the culprit. However, after upgrading the Guest VM crashes directly after login and winds up in the Aborted state.

Logs from GA install:

Code: Select all

Verifying archive integrity... All good.
Uncompressing VirtualBox 6.1.10 Guest Additions for Linux........
VirtualBox Guest Additions installer
Removing installed version 5.2.22 of VirtualBox Guest Additions...
Copying additional installer modules ...
Installing additional modules ...
VirtualBox Guest Additions: Starting.
VirtualBox Guest Additions: Building the VirtualBox Guest Additions kernel 
modules.  This may take a while.
VirtualBox Guest Additions: To build modules for other installed kernels, run
VirtualBox Guest Additions:   /sbin/rcvboxadd quicksetup <version>
VirtualBox Guest Additions: or
VirtualBox Guest Additions:   /sbin/rcvboxadd quicksetup all
VirtualBox Guest Additions: Building the modules for kernel 4.15.0-106-generic.
update-initramfs: Generating /boot/initrd.img-4.15.0-106-generic
VirtualBox Guest Additions: Running kernel modules will not be replaced until 
the system is restarted
Press Return to close this window...

Logs are attached.

Thanks in advance for any help you can provide!

[I excrete rainbows daily]

I tried the solution here: viewtopic.php?f=3&t=98670

...but that immediately resulted in graphics issues, namely the screen no longer resizes correctly and portions of the screen do not redraw until moused over.