clients crash after virtual box update

[alangh]

I have been running virtualbox (recent version that you get from apt-get) on an ubuntu 14.04 LTS host. There was just a "normal" update via System Tools -> Administration -> Software Updater that updated virtualbox to 4.3.34_Ubuntu r104062 . Now when I try to run a guest os (ubuntu 14.04) or start a new guest with ubuntu 15.10 the guest crashes as it tries to start up.

From the virtual box log (on this specific occasion when attempting to start with the 15.10 iso), the crucial lines appear to be:

00:00:31.838258 Guest Log: BIOS: Booting from CD-ROM...
00:00:32.028360 Display::handleDisplayResize(): uScreenId = 0, pvVRAM=00007f821b400000 w=640 h=480 bpp=16 cbLine=0x500, flags=0x1
00:00:32.028379 UIFrameBuffer::RequestResize: Screen=0, Format=843204434, BitsPerPixel=16, BytesPerLine=1280, Size=640x480, Sending to async-handler..
00:00:32.028436 UIFrameBufferQImage::resizeEvent: Format=843204434, BitsPerPixel=16, BytesPerLine=1280, Size=640x480
00:00:32.028445 UIFrameBufferQImage::resizeEvent: Resizing to FALLBACK buffer due to format is invalid..
00:00:45.670222 Display::handleDisplayResize(): uScreenId = 0, pvVRAM=0000000000000000 w=720 h=400 bpp=0 cbLine=0x0, flags=0x1
00:00:45.670249 UIFrameBuffer::RequestResize: Screen=0, Format=0, BitsPerPixel=0, BytesPerLine=0, Size=720x400, Sending to async-handler..
00:00:45.670375 UIFrameBufferQImage::resizeEvent: Format=0, BitsPerPixel=0, BytesPerLine=0, Size=720x400
00:00:45.670384 UIFrameBufferQImage::resizeEvent: Resizing to FALLBACK buffer due to format is invalid..
00:00:45.670845 Guest Log: BIOS: KBD: unsupported int 16h function 03

I am guessing that some kind of local preferences file is corrupted. Can anyone suggest how to get the virtualbox guests running again? I have tried:

sudo apt-get purge virtualbox
sudo apt-get install virtualbox
sudo apt-get install virtualbox-guest-additions-iso

and that did not work.

[Perryg]

Partial logs are useless.

Post the complete log as an attachment.

[alangh]

The VBox.log is attached.

[Perryg]

VirtualBox VM 4.3.34_Ubuntu r104062 linux.amd64 (Nov 23 2015 18:06:43) release log
00:00:00.276262 Package type: LINUX_64BITS_GENERIC (OSE)
00:00:00.298283 Oracle VM VirtualBox Extension Pack (Version: 4.3.10 r93012; VRDE Module: VBoxVRDP)

Update the extension pack to match the running version of VirtualBox.
If this does not fix it then you will need to ask the distro where you get VirtualBox or remove it and install the official version from virtualbox.org if yuo want help here.

[alangh]

That did it, it is working. The ubuntu update to virtualbox, for some reason, had not included the extension pack. With it downloaded and installed from the virtualbox website things worked. Thanks very much!