Bug#1125273: Black screen flash during GDM to GNOME session transition after 13.3 upgrade

[Simon McVittie]

Control: severity -1 minor
Control: tags -1 + trixie moreinfo

On Sun, 11 Jan 2026 at 20:04:30 +0100, ajmasia wrote:
>After upgrading from Debian 13.2 to 13.3, the transition from GDM to the
>GNOME session shows a momentary black screen (flash) instead of the
>smooth animation that existed before.

Not having a perfectly smooth animation is not a serious bug, and we 
have plenty of higher priorities. However, this might be related to 
other regressions that are more serious (#1125941, #1126174, #1125275) 
so it seems worthwhile to investigate.

>- Reproducible on 2 different machines (desktop and laptop)
>- Desktop GPU: AMD Phoenix3 (RDNA3 integrated graphics)

What graphics hardware is in the laptop? If this is related to the more 
serious regressions, then I suspect the answer is going to be some sort 
of AMD GPU.

If you look at the system log (systemd Journal) during one of the 
startups where the black screen flash existed, are there warning 
messages at that time? Specifically, I wonder whether you see

     Page flip failed: drmModeAtomicCommit: Invalid argument

because if you do, that links this to #1125941 and #1126174.

On Mon, 12 Jan 2026 at 16:39:37 +0000, Antonio José Masiá wrote:
>3. Downgraded all affected packages:
>
>   $ sudo apt install \
>       mutter-common=48.4-2 \
>       libmutter-16-0=48.4-2 \
>       gir1.2-mutter-16=48.4-2 \
>       mutter-common-bin=48.4-2 \
>       gnome-shell=48.4-1~deb13u1 \
>       gnome-shell-common=48.4-1~deb13u1 \
>       gnome-shell-extension-prefs=48.4-1~deb13u1

If you upgrade the mutter family of packages back to their versions from 
Debian 13.3, but keep the gnome-shell packages held back to 48.4, is 
that sufficient to work around this?

What about if you downgrade the mutter family of packages to 48.4, but 
upgrade the gnome-shell family to 48.7?

That would tell us whether this is a regression in mutter or in 
gnome-shell, which would help to narrow it down.

     smcv