Bug#1107988: German “ä” key not working on Raspberry Pi 5 with Debian 12

Package: keyboard-configuration

Version: 1.221rpt1

On my Raspberry Pi 5 (Model B Rev 1.0) running Debian GNU/Linux 12 (Bookworm) aarch64, the lowercase “ä” key does not work on any connected keyboard (tested with several Bluetooth and USB keyboards, all with German layout). The issue persists regardless of keyboard model or connection type.

Device: Raspberry Pi 5 Model B Rev 1.0

OS: Debian GNU/Linux 12 (Bookworm) aarch64

Kernel: 6.12.25+rpt-rpi-2712

Keyboards tested: Multiple (Bluetooth and USB, German layout, including 65% and standard size)

Issue: Pressing the “ä” key produces no input. In `xev`, no KeyPress/KeyRelease event is generated for this key, only a KeymapNotify event. All other keys work as expected.

What I tried:

- Verified keyboard layout (`de`, `de-t3`, `de-nodeadkeys`, etc.)

- Used `setxkbmap` and reconfigured `/etc/default/keyboard`

- Upgraded all packages (`sudo apt full-upgrade`)

- Edited `/etc/X11/xorg.conf.d/10-keyboard.conf`

- Set `HID2HCI_ENABLED=1` in `/etc/default/bluetooth`

- Tested with different user accounts and fresh installs

- Tested on Ubuntu Asus machine: **The “ä” key works perfectly there!**

Expected behavior:

The “ä” key should produce the character “ä” (adiaeresis) as on other Linux distributions.

Actual behavior:

No character is produced, and no KeyPress/KeyRelease event is detected in `xev`.

Steps to reproduce:

1. Install Debian 12 (Bookworm) aarch64 on Raspberry Pi 5

2. Connect a German-layout keyboard (Bluetooth or USB)

3. Set keyboard layout to “de”

4. Try to type “ä” (lowercase)

5. Observe that nothing happens and `xev` shows no key event

Additional information:

This issue affects all tested keyboards and persists after all configuration and upgrade attempts. It does **not** occur on Ubuntu amd hardware