VNC output scrambled during Ubuntu installation

[MrSmith]

I ran VirtualBox headless on a FreeBSD 10.1 server (host) and tried to install Ubuntu 14.10 as a guest from the live iso image. I connect to the VirtualBox VNC server to get the VM output. The Ubuntu VM boots up, my VNC client shows the Ubuntu splash screen but as soon as the Ubuntu desktop gets started I get a scrambled image. I can confirm the problem on FreeBSD 9.3 / VirtualBox 4.2.16 and FreeBSD 10.1 / VirtualBox 4.2.16 & VirtualBox 4.2.22. I have tried different VNC viewer @ Ubuntu (ssvncviewer) and Windows (RealVNC), no difference.

VM VNC output

Steps to create the VM:

• set VM='Ubuntu_14.10'
• VBoxManage createvm --name $VM --ostype "Ubuntu_64" --register
• VBoxManage storagectl $VM --name "SATA Controller" --add sata --controller IntelAHCI
• VBoxManage storageattach $VM --storagectl "SATA Controller" --port 1 --type dvddrive --medium ~/ubuntu-14.10-desktop-amd64.iso
• VBoxManage modifyvm $VM --memory 2048 --vram 128
• VBoxManage modifyvm $VM --vrdeproperty VNCPassword=password
• VBoxHeadless -s $VM

Output from VBoxHeadless

Oracle VM VirtualBox Headless Interface 4.3.22_OSE
(C) 2008-2015 Oracle Corporation
All rights reserved.

24/02/2015 22:28:30 Listening for VNC connections on TCP port 3389
24/02/2015 22:28:30 Listening for VNC connections on TCP6 port 5900
VRDE server is listening on port 3389.
24/02/2015 22:28:34   other clients:
24/02/2015 22:28:34 Client Protocol Version 3.8
24/02/2015 22:28:34 Protocol version sent 3.8, using 3.8
24/02/2015 22:28:34 rfbProcessClientSecurityType: executing handler for type 2
24/02/2015 22:28:34 Pixel format for client 192.168.0.109:
24/02/2015 22:28:34   32 bpp, depth 24, little endian
24/02/2015 22:28:34   true colour: max r 255 g 255 b 255, shift r 16 g 8 b 0
24/02/2015 22:28:34 Enabling X-style cursor updates for client 192.168.0.109
24/02/2015 22:28:34 Enabling full-color cursor updates for client 192.168.0.109
24/02/2015 22:28:34 Enabling cursor position updates for client 192.168.0.109
24/02/2015 22:28:34 Enabling KeyboardLedState protocol extension for client 192.168.0.109
24/02/2015 22:28:34 Enabling NewFBSize protocol extension for client 192.168.0.109
24/02/2015 22:28:34 Enabling SupportedMessages protocol extension for client 192.168.0.109
24/02/2015 22:28:34 Enabling SupportedEncodings protocol extension for client 192.168.0.109
24/02/2015 22:28:34 Enabling ServerIdentity protocol extension for client 192.168.0.109
24/02/2015 22:28:34 Enabling Xvp protocol extension for client 192.168.0.109
24/02/2015 22:28:34 Using hextile encoding for client 192.168.0.109
24/02/2015 22:28:38 Sending rfbEncodingNewFBSize for resize to (720x400)
24/02/2015 22:29:04 Sending rfbEncodingNewFBSize for resize to (1024x768)
24/02/2015 22:29:06 Sending rfbEncodingNewFBSize for resize to (1152x400)

Output from ssvncviewer (VNC client)

Proto: RFB 003.008

Connected to RFB server, using protocol version 3.8

SelectSecurityType:
  sec-type[0]    2  (rfbSecTypeVncAuth)
Security-Type:   2  (rfbSecTypeVncAuth)  Latency: 3.01 ms

Performing standard VNC authentication
VNC Password: 
VNC authentication succeeded

Desktop name "VBoxVNC"

VNC server default format:
  32 bits per pixel.  Least significant byte first in each pixel.
  True colour: max red 255 green 255 blue 255, shift red 0 green 8 blue 16
Warning: Cannot convert string "-*-helvetica-medium-r-*-*-12-*-*-*-*-*-*-*" to type FontStruct
Using default colormap which is TrueColor.  Pixel format:
  32 bits per pixel.  Least significant byte first in each pixel.
  True colour: max red 255 green 255 blue 255, shift red 16 green 8 blue 0
geometry: 720x400+358+238 ycrop: 0
create_image()
try_create_image: shm image create fail: image == NULL
try_create_image: created *non-shm* image: 720x400
try_create_image: image->bytes_per_line: 2880

guessed: -compresslevel 1
guessed: -qualitylevel  9
enabling 'delay_sync' mode for faster local drawing,
disable via env SSVNC_DELAY_SYNC=0 if there are painting errors.
New Size: 1024x768 at (0, 0)
ReDoDesktop: ycrop: 0
reset_image: destroyed 'image'
create_image()
try_create_image: shm image create fail: image == NULL
try_create_image: created *non-shm* image: 1024x768
try_create_image: image->bytes_per_line: 4096
New Size: 1152x400 at (0, 0)
ReDoDesktop: ycrop: 0
reset_image: destroyed 'image'
create_image()
try_create_image: shm image create fail: image == NULL
try_create_image: created *non-shm* image: 1152x400
try_create_image: image->bytes_per_line: 4608

[MrSmith]

scrambled vnc output

[Frank Mehnert]

This is something where we expect user input. VNC is not officially supported by the VBox developer team. The VNC source code is part of the VBox sources.