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Fair warning: the Trixie update does not allow you to roll back. It is in theory possible but practically it not only fails every single time, but leaves the sy

Fair warning: the Trixie update does not allow you to roll back. It is in theory possible but practically it not only fails every single time, but leaves the system in an inconsistent and broken state. (Code for 'soon to be unbootable'). What this means is when you find out stuff breaks, like drivers and application software, and decide the upgrade was a bad idea, you are fucked. More notably, some of the upgrade is irreversible - like MySQL/MariaDB. The database binary format is upgraded during the upgrade. So if you discover something else broke, and you want to go back, it's going to take some work. Ask me how I know.

bityard 1y ago
That has never been supported: https://wiki.debian.org/SystemDowngrade https://wiki.debian.org/SystemDowngrade
- sugarpimpdorsey 1y ago
  I said possible, not supported. Too many bits of 'advice' on Stack Overflow, etc. claiming it's possible as top Google results. I'm here to say unequivocally: it does not work, will not work, and will leave the system in an irreversibly broken state. Do not attempt.
  - sigio 1y ago
    Well... then it's always been possible, if you use LVM and create a snapshot before upgrading, then you can revert your snapshot in case it breaks. But this isn't something that would be 'out of the box'... but that's why we make backups, but I can't remember an dist-upgrade ever significantly bricking my systems.
gilbertbw 1y ago
The page about upgrading [0] does have this warning: Back up your data Performing a release upgrade is never without risk. The upgrade may fail, leaving the system in a non-functioning state. USERS SHOULD BACKUP ALL DATA before attempting a release upgrade. DebianStability contains more information on these steps. [0] https://wiki.debian.org/DebianUpgrade https://wiki.debian.org/DebianUpgrade
- sugarpimpdorsey 1y ago
  Yet Windows will let you roll back an upgrade with a single click within 10 days. Of course anyone can restore from backups. It's a pain and it's time consuming. My post serves more as a warning to those who may develop buyer's remorse.
  - BoredPositron 1y ago
    You know imaging your machine is still an option...
    - mikae1 1y ago
      But you can't do that on a live system as you can with Windows or macOS. Not a problem for pre release upgrade perhaps. But I'm so missing this feature from macOS.
      - pak9rabid 1y ago
        You can if you're using LVM. Take a snapshot of the logical volume your system is on, then run `dd' against the snapshot, as it's essentially a frozen point-in-time. I've used this trick many times in a live, rw environment.
      - SAI_Peregrinus 1y ago
        You can snapshot the filesystem if you're using BTRFS, ZFS, or another Copy-on-Write filesystem.
      - hysan 1y ago
        Depends on your filesystem. For example, I certainly can as I’m using btrfs. I’m also using Timeshift for easy management of snapshots. As others have mentioned, there are other choices too like Snapper that all work well.
  - jraph 1y ago
    You might like snapshot based solutions like Snapper
paulv 1y ago
> Ask me how I know. What problems did you have that made you want to roll back the update?
- sugarpimpdorsey 1y ago
  I had some containerized application software break and start misbehaving in odd ways which was indicative of a deeper incompatibility issue. Possibly GPU related. No time to debug, had to roll it back. This was complicated by the fact that the machine also hosted a MySQL database which could not be easily rolled back because the database was versioned up during the upgrade.
  - tremon 1y ago
    Wait, the containerized application broke because of a host upgrade? That's some leaky container you have there. This sounds like a business setting, so this sounds like a good opportunity to advocate for testing hardware, a testing budget, a rollout plan, and a sound backup strategy.
- bobmcnamara 1y ago
  For me it's usually been GPU driver compatibility.
esaym 1y ago
You should be using an lvm snapshot. You are not even making a valid complaint.
yjftsjthsd-h 1y ago
In all fairness... How would that work? Not even just on Debian; in the general case, I don't see how to avoid that other than full filesystem snapshots or backups of some sort. Even on, say, a NixOS system where rolling back all the software and config (basically, /, /usr, and /etc) to exactly its old config is as easy as rebooting and picking the old generation, databases will still have migrated their on-disk format.
- JdeBP 1y ago
  Indeed. Snapshots. And they are a breeze on operating systems where ZFS for everything is available. It's not like the Windows feature of the same name, which I suspect is in part what makes people wary of the idea. That works rather differently. A ZFS snapshot completes in seconds.

bityard 1y ago

That has never been supported: https://wiki.debian.org/SystemDowngrade https://wiki.debian.org/SystemDowngrade

sugarpimpdorsey 1y ago
I said possible, not supported. Too many bits of 'advice' on Stack Overflow, etc. claiming it's possible as top Google results. I'm here to say unequivocally: it does not work, will not work, and will leave the system in an irreversibly broken state. Do not attempt.
- sigio 1y ago
  Well... then it's always been possible, if you use LVM and create a snapshot before upgrading, then you can revert your snapshot in case it breaks. But this isn't something that would be 'out of the box'... but that's why we make backups, but I can't remember an dist-upgrade ever significantly bricking my systems.

gilbertbw 1y ago

The page about upgrading [0] does have this warning: Back up your data Performing a release upgrade is never without risk. The upgrade may fail, leaving the system in a non-functioning state. USERS SHOULD BACKUP ALL DATA before attempting a release upgrade. DebianStability contains more information on these steps. [0] https://wiki.debian.org/DebianUpgrade https://wiki.debian.org/DebianUpgrade

sugarpimpdorsey 1y ago
Yet Windows will let you roll back an upgrade with a single click within 10 days. Of course anyone can restore from backups. It's a pain and it's time consuming. My post serves more as a warning to those who may develop buyer's remorse.
- BoredPositron 1y ago
  You know imaging your machine is still an option...
  - mikae1 1y ago
    But you can't do that on a live system as you can with Windows or macOS. Not a problem for pre release upgrade perhaps. But I'm so missing this feature from macOS.
    - pak9rabid 1y ago
      You can if you're using LVM. Take a snapshot of the logical volume your system is on, then run `dd' against the snapshot, as it's essentially a frozen point-in-time. I've used this trick many times in a live, rw environment.
    - SAI_Peregrinus 1y ago
      You can snapshot the filesystem if you're using BTRFS, ZFS, or another Copy-on-Write filesystem.
    - hysan 1y ago
      Depends on your filesystem. For example, I certainly can as I’m using btrfs. I’m also using Timeshift for easy management of snapshots. As others have mentioned, there are other choices too like Snapper that all work well.
- jraph 1y ago
  You might like snapshot based solutions like Snapper

paulv 1y ago

> Ask me how I know. What problems did you have that made you want to roll back the update?

sugarpimpdorsey 1y ago
I had some containerized application software break and start misbehaving in odd ways which was indicative of a deeper incompatibility issue. Possibly GPU related. No time to debug, had to roll it back. This was complicated by the fact that the machine also hosted a MySQL database which could not be easily rolled back because the database was versioned up during the upgrade.
- tremon 1y ago
  Wait, the containerized application broke because of a host upgrade? That's some leaky container you have there. This sounds like a business setting, so this sounds like a good opportunity to advocate for testing hardware, a testing budget, a rollout plan, and a sound backup strategy.
bobmcnamara 1y ago
For me it's usually been GPU driver compatibility.

esaym 1y ago

You should be using an lvm snapshot. You are not even making a valid complaint.

yjftsjthsd-h 1y ago

In all fairness... How would that work? Not even just on Debian; in the general case, I don't see how to avoid that other than full filesystem snapshots or backups of some sort. Even on, say, a NixOS system where rolling back all the software and config (basically, /, /usr, and /etc) to exactly its old config is as easy as rebooting and picking the old generation, databases will still have migrated their on-disk format.

JdeBP 1y ago
Indeed. Snapshots. And they are a breeze on operating systems where ZFS for everything is available. It's not like the Windows feature of the same name, which I suspect is in part what makes people wary of the idea. That works rather differently. A ZFS snapshot completes in seconds.