[Solved] Lock screen freezes LinuxMint 19.1 guest on VirtualBox 5.2.26

[viboxer]

Just to report a bug:

• Host: Windows 10 Pro 64bit 1703 (OS build 15063.0) with VirtualBox v5.2.26.r127414
• Guest: Linux Mint 19.1 "Tessa" Cinnamon 64bit with VBox_GAs_5.2.26 installed with 3D acceleration activated 128MB Video Memory and 8192 RAM.

Locking the screen will minimize all windows and freeze user interface, can move mouse cursor but cannot click on anything, keyboard also not working (tried sending keyboard shortcuts like ALT+F2, ALT+TAB).

To reproduce:

• Install VirtualBox 5.2.26 on Windows 10 Pro 64bit
• Create and install Linux Mint 19.1 64bit as guest
• Install VBox Guest Addition 5.2.26 on Linux Mint 19.1 guest
• Menu button -> Lock screen
• Alternatively let time to pass with inactivity to trigger automatic screen lock

NOTE1: I did not have this problem with VirtualBox 5.2.22
NOTE2: processes in background work but there is no way to interact with the guest operating system. You'll have to reset the guest machine.

EDIT1: Figured out: it's happening only if in the Display settings, the 3D Acceleration is enabled. So as workaround for this bug, just disable 3D Acceleration or disable screensaver so Linux Mint will never activate screen lock.

EDIT2: tested on another guest running Linux Mint 17.3 64bit with the same VBox Guest Addition 5.2.26 and 3D acceleration enabled, and not experiencing this problem.

[GrahamV]

I've got the same issue with Linux Mint 19.1 Cinnamon

Similar setup i7-4790 desktop Windows 10 Pro 64bit 1703 host running a Linux Mint 19.1 Cinnamon guest, but I also had this issue with a Linux Mint 18.3 Cinnamon guest.

I also tried Virtual Box 6 but that had the issue as well so I've reverted to 5.2.22 (5.2.24 also had the issue).

As well as the lock screen completely freezing the screen, I also found that trying to get a TTY session with CTRL+ALT+F6 caused the issue. Instead of a terminal login it just shrunk the Cinnamon graphical screen down into the centre of the screen. CTRL+ALT+F7 went back to fullscreen but then it was completely frozen and only a VM reset would work.

It seems to be an Intel display issue because I also have a laptop with AMD Ryzen 5 CPU (Win 10 Home) and the issue doesn't occur with that. Linux Mint 19.1 Cinnamon runs fine in Virtual Box 6 with 3D acceleration enabled on the laptop.

[shankar2k]

I also have been having this problem.

• Host: Windows 10 Home 64bit (OS Build 17134.0) with VirtualBox Version 5.2.26 r128414 on a ThinkPad T480 w/ i7-8650U CPU
• Guest: Linux Mint 19.1 "Tessa" Cinnamon 64bit with VBox_GAs_5.2.26 installed with 3D acceleration activated 128MB Video Memory and 4096 RAM.

I disabled 3D acceleration, and so far the system hasn't frozen yet, even when I activate the lock screen.

I have attached the last vbox.log when my system froze. The last message in the log before I shut down the VM is:

02:52:32.040880 OpenGL Error: crUnpackExtendWindowVisibleRegion: parameter 'cRects' is out of range

Is that what is causing the bug?

[socratis]

I disabled 3D acceleration, and so far the system hasn't frozen yet, even when I activate the lock screen.

That helps. Also what helps is to disable the screensaver and all power management from within the guest. Leave the power management and the screen locking to the host.

[viboxer]

I also confirm that on the frozen screen without a visible login input, "entering" the password will unlock and unfreeze the screen, as described in this other thread: viewtopic.php?f=3&t=91915. Anyway I prefer the solution of disabling the screensavers and energy savings settings.

Or just by turning off the computer lock from the screensaver settings: Menu -> Preferences -> Screensaver -> Settings -> Lock settings -> disable "Lock the computer when put to sleep" and "Lock the computer after the screensaver starts". This way even if the screensaver will fail to start showing the desktop as if everything was minimized, mouse-over will return your desktop without freezing.