Keyboard map was overwritten when upgrade from bookworm to trixie.

I was unable to log-in since I can not use my own keyboard symbols map.
My password was interpreted with wrong symbols since they were modified
by the upgrade.

The apt/installer/upgrader should have checked by `diff` and prompt user
when found changes in the current mapping which in my case was
configured by this line:

```
* keyboard-configuration/layoutcode: vn,us
```

This bug would affect anyone who customizes their own keyboard with X11
and potentially be locked-out of their own system forever.

Trần H. Trung <work@trung.fun> (2025-08-11):

It's not clear to me what the situation was before and after the
upgrade, can you please clarify? Some configuration file diff would be
appreciated to fully understand what the problem is. Bonus points if you
can check upgrade logs to see what happened (/var/log/apt/*.log).

*cough*


Cheers,

Sure I can explain a little further…

The situation before upgrade was that I was using my own keyboard:
» https://soft.trung.fun/ban-phim/ban-phim.en.html#cai-dat

which modified the symbol file `/usr/share/X11/xkb/symbols/vn`

For specific content of my (publicly available) symbol file:
» https://soft.trung.fun/ban-phim/src/

This symbol file was overwritten when I upgraded to Trixie.

There was warning about some changes of keyboard config but it was not
clear that it had over-written this symbol file. I think French and
Greek was mentioned but there was no mention of Vietnamese (or any other
languages). My customized symbol file and hence my keyboard continued to
work as expected after `apt` has finished upgrading since it was loaded
in RAM and X11 never received signal to reload the newly installed
symbol file. The problem surface only after reboot when the system loads
the newly installed file.

Because the new file installed is nothing like the symbol file before
upgrading, there was no way for me (or anyone who have customized their
keyboard regardless of which languages) to write the correct password to
log-in. In my case, it was password, I think this can potentially cause
problem for writing correct username too.

This is as specific as I can go unless I reveal my own things.

If SSH and `sshd` were not configured to accept log-in via key-pair, I
can't think of any other way to log-in.

—————————————
Trần H. Trung
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https://trung.fun
tel:+84-794-819-533
mailto:work@trung.fun
xmpp:trần.h.trung@trung.fun
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