I recently updated my Debian desktop to Trixie. It went fine but Grub
broke. It got as far as "Welcome to GRUB" then black screen and reboot.

I fixed that by doing grub-install and update-grub in a chroot but what
went wrong and can I avoid this annoyance in the future? Is this a known problem? I remember seeing an off hand mention that this "often" happens
on Debian and derivatives but didn't pursue it then and don't have a
reference. And it's never happened to me before.

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

anssi.saari@debian-user.mail.kapsi.fi wrote:

I recently updated my Debian desktop to Trixie. It went fine but Grub
broke. It got as far as "Welcome to GRUB" then black screen and reboot.

I fixed that by doing grub-install and update-grub in a chroot but what
went wrong and can I avoid this annoyance in the future? Is this a known >problem? I remember seeing an off hand mention that this "often" happens
on Debian and derivatives but didn't pursue it then and don't have a >reference. And it's never happened to me before.

Running grub-install by hand is only ever a *temporary* fix here. You
don't say if you're using BIOS boot or UEFI boot. There's a couple of
likely possibilities for the cause of your problem.

Problem 1: inconsistent grub-core and grub modules ==================================================

BIOS boot is more likely to see this problem here, but it's also
possible on UEFI systems.

On a BIOS-booting system, the first-stage GRUB loader (grub core) is
the bit that gets installed by "grub-install". This fits in the first
megabyte of your hard disk. Unfortunately, there's a lot more to GRUB
such that it won't all fit there and the rest of it lives in
/boot/grub on your installed system.

The problem that comes out of this is that the versions of the grub
core code and the modules need to be compatible. The API between those
pieces is *not* fixed, and so if you don't ensure that they are
upgraded in sync you can get all kinds of weird booting problems. The
worst part of those problems is that they'll often only show up a long
time *after* you maybe broke things by doing a manual "grub-install" - typically after a major version change in GRUB during an upgrade
between versions of Debian.

On a UEFI-booting system that needs to boot using the removable media
path (often because of firmware bugs) can also fall into this trap. If
you've installed to the removable media path *by hand* using
"grub-install" then you can end up with an old grub-core EFI binary
there which is never upgraded. All works great, until one day it
doesn't. :-(

GRUB itself can't know exactly which disk(s) you installed it onto, so
the package maintainer scripts add extra logic to track this. The
*correct* way to fix things on a Debian system is to run:

# dpkg-reconfigure grub-pc
(for BIOS)

or

# dpkg-reconfigure grub-efi-amd64
(for UEFI on and amd64 machine)

and answer the questions, ioncluding (for BIOS) which disks to install
to and (for UEFI) whether you need to install to the removable media
path. This will solve the problem of broken boot for you
*persistently* and should survive future upgrades.

Problem 2: Secure Boot issues on UEFI
=====================================

Again, this can be caused by running "grub-install" and not using the maintainer scripts. As things move on, it's possible that your system
can have old *security-blocked* versions of GRUB or shim in the boot
path. If GRUB doesn't know where to install things on package
upgrades, they never get updated to the newer, working versions.

The fix (again) is to run dpkg-reconfigure once you have your system
booting.

Finally...

If you end up swapping the disks in your computer (e.g. to replace
failed disks), make sure you re-run dpkg-reconfigure afterwards to
make sure the system is fully configured - *don't* be tempted to just
run grub-install...

Hope this helps!

Steve (one of the Debian GRUB maintainers)

--
Steve McIntyre, Cambridge, UK. steve@einval.com Can't keep my eyes from the circling sky,
Tongue-tied & twisted, Just an earth-bound misfit, I...

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

fxkl47BF@protonmail.com writes:

did you get an answer for this
i've been looking to upgrade
this list highligths too many problems

I've had the two responses visible on list, but nothing's clear. Of
course, it's hard to figure out what went wrong after the fact. And was
trivial to fix.

To be fair, my five other systems that were updated to Trixie were
problem free.

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Steve McIntyre <steve@einval.com> writes:

Running grub-install by hand is only ever a *temporary* fix here. You
don't say if you're using BIOS boot or UEFI boot. There's a couple of
likely possibilities for the cause of your problem.

Thanks for the response and sorry about the missing information. UEFI
system, secure boot off. No removable media workaround either. So I
guess it's the unlikely possibilities that matter here. Now I wish I had
backed up my EFI partition to see what the differences were between
booting system and non-booting system.

If something can be called these days unusual in this system it's that
this is a multiboot system, with Windows 11 and Arch Linux in addition
to Debian. But there's nothing of Arch on the EFI partition, just Debian, Microsoft and a little memtest86 variant.

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

On Thu, 06 Aug 2026 15:57:06 +0000
fxkl47BF@protonmail.com wrote:
Hello fxkl47BF@protonmail.com,

this list highligths too many problems

Because nobody looks for assistance when everything goes without a hitch.
--
Regards _ "Valid sig separator is {dash}{dash}{space}"
/ ) "The blindingly obvious is never immediately apparent"
/ _)rad "Is it only me that has a working delete key?"
You're not so safe in the safety of your room
Nasty - The Damned


--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Brad Rogers <brad@fineby.me.uk> writes:

On Thu, 06 Aug 2026 15:57:06 +0000
fxkl47BF@protonmail.com wrote:

Hello fxkl47BF@protonmail.com,

this list highligths too many problems

Because nobody looks for assistance when everything goes without a hitch.

"Just wanted to drop in and let everyone know that everything is working
as expected!"

-- no one, ever

--
this is my clever sig.

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

Dan Ritter wrote:

Russell S. wrote:

Brad Rogers <brad@fineby.me.uk> writes:

On Thu, 06 Aug 2026 15:57:06 +0000
fxkl47BF@protonmail.com wrote:

Hello fxkl47BF@protonmail.com,

this list highligths too many problems

Because nobody looks for assistance when everything goes without a hitch. >>

"Just wanted to drop in and let everyone know that everything is working
as expected!"

We do get these from time to time, and they are almost always
phrased as

"I upgraded from bookworm to trixie, no problems"

and happen shortly after a new major release. Not many, though.

Much more often we get

"that worked, thanks"

at the end of a thread.

for the record last week i did an update of my stable partition
and it went without any issues at all other than taking some time
to download over my slow connection.

in my day to day running of my Debian testing system i have had
a few issues here or there but nothing major.


songbird

--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)