Ubuntu boots into a blank screen when NetworkManager is enabled

Question

I stumbled upon a peculiar situation in Ubuntu Desktop 22.04.4: If the NetworkManager service is enabled, the PC boots to a gray-colored blank screen, like when the display monitor is off. I would like to ask for help fixing that.

Context

I installed and removed a couple of snap packages, one of them being a VPN client. (I probably did more than that in the last boot, where the system was properly working.) After restarting the PC, it boots to a blank screen.

The default GUI and the X11 windowing system are being used. A single display is attached to the NVIDIA card. The iGPU multi-monitor is enabled in the UEFI. This whole configuration was there for a while and the system worked in a stable manner.

More details of the problem and my troubleshooting efforts are available in the following section.

What I Have Tried

• When NetworkManager is enabled:

  • GDM is configured to automatically log in to my default account. On the blank screen, running Ctrl+Alt+T and typing sudo reboot followed by entering the password of the account and pressing enter/return does not work. I think the desktop environment is not loaded at all.

  • If I switch to another GUI using Ctrl+Alt+F1, I will see a logo of a computer with crossed-out eyes and a down-turned mouth saying:

  Oh no! Something has gone wrong.

  A problem has occured and the system can't recover.

  Please log out and try again.

  , along with a "Log Out" button.

  • I can successfully switch to a new CLI using Ctrl+Alt+F3. Restarting gdm3 does not resolve the concern of the GUI not being loaded.

  • If I press Alt+SysRq+E the blank screen turns into a black screen for a moment, and then the desktop will be loaded. Here, I face two difficulties: First, the network interfaces (Wi-Fi and Ethernet) are not present in the GUI. The GUI settings window notes that I should enable the NetworkManager service. Second, the Windscribe app (which has been installed for a long time) fails to open and demands to be restarted.

  • Restarting NetworkManager fixes the problem of interfaces not being available. However, Windscribe error persists no matter how many times I restart it and regardless of whether or not NetworkManager is restarted.

• When NetworkManager is disabled:

  • In this case, the PC successfully boots to the desktop environment.

  • Here, the problem is that I have to start NetworkManager manually: sudo systemctl start NetworkManager

  • Interfaces, and Windscribe work fine.

  • I can successfully switch to another GUI.

  • Taking a quick look at syslog and NetworkManager logs, nothing jumped out as particularly significant. To be honest, I'm unclear about what exactly I'm supposed to look for.

Related (seemingly not duplicate) Questions:

• My computer boots to a black screen, what options do I have to fix it?
• network-manager crashes

Diagnostics

• Disabling automatic login (suggested by @eyoung100):

  • Action: I disabled NetworkManager (NM); rebooted; disabled automatic login via settings GUI, ensured AutomaticLoginEnable=False in /etc/gdm3/custom.conf, enabled NM again; and rebooted to see the effect.

  • Result: Login screen is visible. After logging in, only a blank screen is seen; changing GUI using Ctrl+Alt+F1 results in the same exact result; using Alt+SysRq+E makes the screen black, and then gray (like the display is off) again. A way to log in is to first end all apps using a system request, then log in via current or the other GUI, both result in network interfaces and Windscribe not working.

  • Result with enabled NM: The result is exactly the same as before even if I disable the NM again and reboot, that is to say, I cannot log in regardless of the status of NM when automatic login is disabled.