Can Guest Additions be removed if it prevents you from even logging in?

[jnb]

As per my post viewtopic.php?f=3&t=84664&p=402057 in this forum below, having upgraded a working VB 5.1.26 to 5.1.28 and installing the corresponding 5.1.28 VBOX Guest Additions I am completely locked out from an existing Linux guest, unable to log in (I do not have a copy of the VBox image prior to the upgrade, it did not occur to me that I could lose access to the whole thing.)

Since unfortunately no answer to that post has been forthcoming, it seems to me that the only way to recover is to downgrade to VBox 5.1.26. However at that point my image will have the "faulty" 5.1.28 Guest Additions, which will either not work with VBox 5.1.26 or will replicate the problem.

Is it possible to remove the Guest Additions completely (or downgrade that to 5.1.26) while I am unable to log into the OS? Excuse my ignorance, but I'm thinking that the Guest Additions is a component which has been installed into the OS, not just something which runs in VB, so that will not be possible?

I really should be most obliged for some answer/help, otherwise I seem to have lost my VM completely...

[Perryg]

I would first make sure that 3D acceleration is disabled in the guest settings and then see if you can boot properly. If so then you can remove the guest additions and install the ones that match your running version of VirtualBox. If this does not allow you to get to a login screen then boot the guest and once it settles down press the host+F1 or host+F2 to get to a tty window. There you can remove the additions and install the proper ones using normal Linux commands.

[jnb]

@Perryg
First, thank you very much for replying.

Neither 3D nor 2D acceleration is enabled in VBox on either image. The VBox settings are identical for the one which I can no longer log into and for the one which still works.

Might I very respectfully ask if you would be kind enough to look at my post here viewtopic.php?f=3&t=84664&p=402057 There you will see that having successfully upgraded to VB 5.1.28, once I then went into OS and let it upgrade to exactly correct Guest Additions 5.1.28 I became unable to ever log in again.

So it's not that that I need to "remove the additions and install the proper ones", I already have the 5.1.28 Additions to correspond to the new 5.1.28 VBox version. The problem is that has locked me out! I don't want to have to go to the performance of downgrading back to 5.1.26, it's that I cannot see how to get back to working again any other way. I attached my VBox.log to that post to show the problem logging in, and was really hoping for some response from you knowledgeable guys. I do totally understand and respect that I am not "entitled" to help there, but really hoped someone would have to something to say from the log to help, given that installing a standard upgrade to VBox has locked me out and I am now "stuck".

I'd be really, really grateful if you (or someone) would have a look at viewtopic.php?f=3&t=84664&p=402057 and see if you can advise how best to proceed. My thanks in advance.

[Perryg]

I understand but the guest is where the problem is and I have given you a way to get back to a working state. The guest additions do not need to match the version of VirtualBox you are running as long as the major version does not change 5.* to 6.*, Etc. I would remove the installed guest additions and see if it boots by dropping to a tty as I indicated. Did you try that and did it not show a terminal prompt?

[jnb]

@PerryG
Fair enough, and thank you for your further reply (which crossed with my PM to you as it was so rapid!).

At present I am not at the machine hosting the problematic VM. I will do so as soon as I can, and of course report back. Thank you for confirming this is the way to go. (I presume that the VBox.log I attached to the other post does not give you experts enough to actually pinpoint the problem?)

May I ask: I am only used to installing the Guest Additions via the Devices menu in VB. Is there a VBox page explaining what to do to uninstall the GA once they have been installed from within Linux?

Thank you so much for your time.

[Perryg]

If the additions you have installed is still attached to the guest just run the again with the flag uninstall at the end. If you can actually reach the terminal and log in then you need to mount the CD/DVD first, then access it and run the install with the uninstall option

sudo mount /dev/sr0 /media will mount them in the /media folder and you can access them from there.

[jnb]

Thank you.

Given that I am going to try uninstalling GA 5.1.28 and try again with GA 5.1.26, should I indeed first downgrade VBox to 5.1.26 before doing so or can I/is it worth trying GA 5.1.26 while still running the VBox 5.1.28 I have presently upgraded to?

[Perryg]

First steps first my friend. Let's see if removing the GAs that are installed allows the guest to boot normally. No need to downgrade the host yet, especially since you said that one guest does work.

[jnb]

@PerryG

Progress report, as promised:

1. Used <Ctrl>+F1/F2 to create terminal login. (Didn't know about these! Very useful. I don't see that VBox offers these off its menu...)
2. Huge difficulty using terminal, as every few seconds window would resize/flip back to its bad state. Keep using <Ctrl>+F2 to (sometimes) get back and type a few more characters...
3. Managed to uninstall GA 5.1.28, and reboot.
4. No difference in behaviour --- normal window still resizing/unusable.
5. Uninstalled VB 5.1.28 completely, reinstalled VB 5.1.26 from scratch, plus its ExtPack version, no GA. No difference in behaviour.
6. Installed GA 5.1.26. Installation without hitch. However, same behaviour.
7. Managed to get in from F1; found `apt-get upgrade` things to do (surprised me there were any...).
8. Now, lo & behold, finally able to access desktop at last!
9. Upgraded VBox + ExtPack 5.1.26 -> 5.1.28, still with old 5.1.26 GA. Still working without problem. Yay!!
10. Let it upgrade GA 5.1.26 -> 5.1.28. Ubuntu reports (more than one) errors during install. Unable to access details, as clicking for them resulted in endless hang.
11. Reboot. Still able to log into desktop. But doing things again resulted in Ubuntu errors. No idea what.
12. Smoked some cigarettes, to give it some time, and calm my nerves.
13. Reboot again. So far, no Ubuntu errors....

Conclusion: Who knows?! Maybe suspect whole Guest state, maybe suspect problem with GA 5.1.28 under Ubuntu 17.04.

Next Steps:

• Try home machine which has an Ubuntu 17.04 image allowing it to upgrade VB 5.1.26 -> 5.1.28 and see what happens. (Will first keep a copy of the whole VDI as it is now under 5.1.26 that I can revert to.) Hoping to see whether GA 5.1.28 does or does not have a problem under Ubuntu 17.04.
• When I am less frazzled, tempted to wipe faulty Ubuntu 17.04 image and reinstall whole OS from scratch, because I'm not sure I like the look of the state it's in...

Sound reasonable? Thanks so much for your clue about how to log into box so that I could start to recover it...

[Perryg]

Under a normal Linux on metal the key combo would be ctrl+alt+F1 or F2 depending on the type of Linux always gets you to a tty window and is not a VirtualBox command. The difference in a virtual guest is you use the host key instead of the ctrl+alt because it has to be different or the host will pick it up instead. From the sounds of it the guest additions install must have been corrupted. Could have been due to missing packages that you installed during the apt-get update. No idea at this point since I did not have actual contact to the machine where I could do proper diagnostics, but the point is you got it to function. Good job!

[jnb]

I have now upgraded a similar but not identical Ubuntu 17.04 VDI image on another Host from VB 5.1.26 to 5.1.28, including ExtPack & Guest Additions. To my (immense) relief, this completed without errors and all looks fine.

I therefore conclude that my issue was a non-reproducible one-off related to the state of my particular image or possibly a glitch in the upgrade, rather than a pathological problem between Ubuntu 17.04 & VBox 5.1.28.

@Perryg
My deep thanks for your concern & help with this issue.