cannot click on host or guest after Ubuntu host upgrade

[andrewz]

After upgrading my host Ubuntu 20.04 to Ubuntu 21.04, I am having issues with the mouse (touchpad).

Symptoms
* Cursor moves properly for host and guest (good).
* Problem sometimes does not happen right away. At first, it works fine.
* Later, touchpad click does nothing for host and guest


System
* VirtualBox Version 6.1.26 r145957 (Qt5.15.2) installed from virtualbox.org
* VirtualBox extension pack 6.1.26r145957
* Host: Ubuntu 21.04
* Guest: Windows 10 20H2 and other Windows 10 builds
* Hardware: Lenovo IdeaPad 330s-15ikb
* Single screen
* Guest is set to USB Tablet

Steps I tried
* Search for solutions online
* While VM is running, disable and reable mouse integration
* Plug in hardware USB mouse, unplug it, and plug it back
* Use touchpad instead of mouse.
* Put guest in full screen or windowed mode
* Reboot guest
* Reboot host
* Look for VBoxClient to kill, but it did not exist https://www.virtualbox.org/ticket/14903

[scottgus1]

Later, touchpad click does nothing for host and guest

Does the click failure ever happen when no Virtualbox VMs or windows are running?

[andrewz]

Later, touchpad click does nothing for host and guest

Does the click failure ever happen when no Virtualbox VMs or windows are running?

No, it only happens when a VM is running. Once the problem starts, I can reliably resolve it (temporarily) by closing the VM. During the shut-down progress while the progress bar is loading, the problem exists, but i's fixed instantly once the VM is fully closed.

[andrewz]

After upgrading host from Ubuntu 21.04 to 21.10, the Windows 10 guest immediately worked much better, but it still sometimes has the problem.

Problem is more severe with Windows 8.1 guest. I updated the drivers through the virtual CD and shut down the VM. I disabled audio and downgraded emulated USB from USB 3 to USB 1. When the clicking problem starts, I can still click Ubuntu desktop manager panel (e.g., calendar, activities) across the top of the screen, but no other part of the host, guest, or VirtualBox UI reacts to left clicks or right clicks. Once problem starts, disabling mouse integration does not reenable clicking on the host, and the problem will continue until the host is closed.

The Ubuntu panel gave me an idea. I logged out of Ubuntu (host) and switched the desktop manager from "Ubuntu" to "Ubuntu on Xorg", and now the Windows 8.1 guest has been working fine.

tl;dr The problem was Wayland, and using GNOME on X.org instead helped (so far).