# LANG=C apt install libegl-mesa0/unstable libgbm1/unstable libgl1-mesa-dri/unstable libglx-mesa0/unstable mesa-libgallium/unstable mesa-vulkan-drivers/unstable
libegl-mesa0 is already the newest version (25.3.3-1).
libgbm1 is already the newest version (25.3.3-1).
libgl1-mesa-dri is already the newest version (25.3.3-1).
libglx-mesa0 is already the newest version (25.3.3-1).
mesa-vulkan-drivers is already the newest version (25.3.3-1).
...
DOWNGRADING:
mesa-libgallium
...
Continue? [Y/n]
dpkg: warning: downgrading mesa-libgallium:amd64 (26.0.0~git20251230-1) to (25.3.3-1)
(Reading database ... 377755 files and directories currently installed.)
Preparing to unpack .../mesa-libgallium_25.3.3-1_amd64.deb ...
Unpacking mesa-libgallium:amd64 (25.3.3-1) over (26.0.0~git20251230-1) ...
dpkg: error processing archive /var/cache/apt/archives/mesa-libgallium_25.3.3-1_amd64.deb (--unpack):
trying to overwrite '/usr/lib/x86_64-linux-gnu/dri/nouveau_drv_video.so', which is also in package mesa-va-drivers:amd64 (26.0.0~git20260120-2)
Errors were encountered while processing:
/var/cache/apt/archives/mesa-libgallium_25.3.3-1_amd64.deb
needrestart is being skipped since dpkg has failed
Error: Sub-process /usr/bin/dpkg returned an error code (1)
Ergebnis: Grafische Sitzung startet nicht mehr.
# apt --f installist erfolglos.
Die "dpkg --force"-Optionen habe ich nicht riskiert.
Ich bin dankbar für Eure Hilfe und liefere gern weitere Informationen zu meiner aktuellen Installation.
