Hello,
I have encountered the following issue on Ubuntu 18, 20, and 22, and now again after upgrading to Ubuntu 24, using Ext4 with LUKS.
Additionally, after performing a fresh install of Ubuntu 24 a few weeks ago with encrypted ZFS (LUKS), the same issue has reappeared—this time more frequently and, as of today, nearly “permanently.”
Regardless of whether I use the laptop’s internal keyboard (HP ProBook 450 G6 or Lenovo Yoga X1 Gen8—note that I just transferred the old SSD to the new Lenovo laptop, and the issue persists) or an external USB keyboard (directly connected or via docking station), the problem remains the same: the input switches to VT100 pseudographics as soon as I press AltGr+Q to produce the “@” symbol. This makes it impossible to enter my passphrase.
On previous versions (e.g., Ubuntu 22 upgraded to 24), rebooting usually solved the problem 99% of the time. However, today was the first time it took over 60 minutes and approximately 30 reboots before I was “lucky” enough to input the passphrase and boot the system.
As a workaround, I created a second LUKS passphrase without the @ symbol, but I would like to address and resolve the root issue.
I have searched extensively but cannot find any information about this specific issue or whether it is expected behavior for Plymouth to allow VT100 mode switching.
Here is what the issue looks like to me:
As you can see, I can press every single key and get the expected character. However, as soon as I press AltGr+Q, it switches to VT100 pseudographics.
As a user in ubuntu irc suggested, its most likely VT100: https://en.wikipedia.org/wiki/Shift_Out_and_Shift_In_characters
Neither CTRL+C, ESC, nor SI/SO Key combinations like CTRL+N, CTRL+O, nor C0/C1 control codes like ^N, ^O, ^[, ^X (https://en.wikipedia.org/wiki/C0_and_C1_control_codes) or any other key Ive tried restores regular character input.
EDIT: One other Keycombination that activates VT100 is some timing related AltGr + Shift. It does not happen when I press both long, but I did manage to go in and out of VT100 Mode by some quick/short combination of those. I was quite certain that AltGr + Q triggered it but maybe its actually AltGr + Shift and only happend due to some fast typing within my passphrase of “Shift + LETTER” followed by “AltGr + Q”
Do you have any ideas about this behavior? Is this intentional?
I asked ChatGPT for suggestions, and it proposed a few solutions. However, after cross-referencing with other sources, I found warnings that some methods might be risky, potentially resulting in an unbootable GRUB if the keyboard is not properly recognized. So, I have refrained from attempting these solutions.
For example, ChatGPT suggested:
sudo apt install console-setup
sudo nano /etc/default/grub
GRUB_TERMINAL_INPUT=“console”
GRUB_CMDLINE_LINUX=“keymap=de”
sudo update-grub
Another suggestion was:
sudo nano /etc/default/keyboard
XKBLAYOUT=“de”
sudo nano /etc/vconsole.conf
KEYMAP=de
sudo update-initramfs -u
I am hesitant to apply these changes without professional advice.
May I kindly ask for your help? Is this issue known or expected, or does it warrant escalation as a bug report? I believe this behavior (switching to VT100 on AltGr+Q) should not exist in the first place.