Guru Alerts from El Capitan / Yosemite Builds

I am getting Guru messages attempting to create a El Capitan build.

Applications: 
  Packer:         1.1.1
  VirtualBox:     5.2.0r118431

Host System
 ProductName:   Mac OS X
 ProductVersion:    10.12.6 
 BuildVersion:  16G1036

STEPS

sudo prepare_iso/prepare_iso.sh ~/Downloads/Install\ OS\ X\ El\ Capitan.app dmg
packer build \
   -var-file=macos1011.json \
   -var iso_url=dmg/OSX_InstallESD_10.11.6_15G31.dmg \
   macos.json

ACTUAL RESULTS

I got a GURU message at the point it is waiting for SSH:

A critical error has occurred while running the virtual machine and the machine execution has been 
stopped.

For help, please see the Community section on https://www.virtualbox.org or your support contract. 
Please provide the contents of the log file VBox.log and the image file VBox.png, which you can find 
in the /Users/joaquin/VirtualBox VMs/macos1011/Logs directory, as well as a description of what you 
were doing when this error happened. Note that you can also access the above files by selecting 
Show Log from the Machine menu of the main VirtualBox window.

Press OK if you want to power off the machine or press Ignore if you want to leave it as is for 
debugging. Please note that debugging requires special knowledge and tools, so it is recommended 
to press OK now.

Log Snippet from attempt with El Capitan:

VirtualBox VM 5.2.0 r118431 darwin.amd64 (Oct 18 2017 08:28:11) release log
00:00:00.991365 Log opened 2017-11-15T19:29:13.218105000Z
00:00:00.991366 Build Type: release
00:00:00.991376 OS Product: Darwin
00:00:00.991381 OS Release: 16.7.0
00:00:00.991385 OS Version: Darwin Kernel Version 16.7.0: Wed Oct  4 00:17:00 PDT 2017; root:xnu-3789.71.6~1/RELEASE_X86_64
00:00:00.991461 DMI Product Name: MacBookPro14,3
00:00:00.991499 DMI Product Version: 1.0
00:00:00.991505 Host RAM: 16384MB (16.0GB) total, 7011MB (6.8GB) available
…
…
…
…
00:00:05.302383 !!
00:00:05.302384 !! {vgagr}
00:00:05.302384 !!
00:00:05.302386 VGA Graphics Controller (3CF): GR index 3CE:08
00:00:05.302389  GR00:00 GR01:00 GR02:00 GR03:00 GR04:00 GR05:40 GR06:05 GR07:0F GR08:FF
00:00:05.302414 !!
00:00:05.302414 !! {vgapl}
00:00:05.302414 !!
00:00:05.302416 read mode     : 0     write mode: 0
00:00:05.302420 set/reset data: 00    S/R enable: 00
00:00:05.302424 color compare : 00    read map  : 0
00:00:05.302428 rotate        : 0     function  : 0
00:00:05.302432 don't care    : 0F    bit mask  : FF
00:00:05.302436 seq plane mask: 0F    chain-4   : on
00:00:05.302440 !!
00:00:05.302440 !! {vgasr}
00:00:05.302441 !!
00:00:05.302443 VGA Sequencer (3C5): SR index 3C4:00
00:00:05.302445  SR00:03 SR01:01 SR02:0F SR03:00 SR04:0A SR05:00 SR06:00 SR07:01
00:00:05.302468 !!
00:00:05.302468 !! {vgatext}
00:00:05.302468 !!
00:00:05.302471 Not in text mode!
00:00:05.302472 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

NOTES

This happens on both El Capitan and Yosemite. It doesn't happen on Sierra, as we get text on the screen.

Not sure what to do or how to proceed, workaround, solutions, etc.

boxcutter / macos

Guru Alerts from El Capitan / Yosemite Builds #29

STEPS

ACTUAL RESULTS

NOTES