How to upgrade xenial for powerpc to its latest version?

quote: I get a lot of errors: "... as repository 'xxx' doesn't support architecture "powerpc"".

As far as I know, the repositories for powerpc still exist for xenial. I assume the first step for getting your system updated is solving the repository problems.

I suggest that you post the output of the commands

dpkg --print-architecture
sudo apt update
find /etc/apt -name '*.list' -exec bash -c 'echo -e "\n$1\n"; cat -n "$1"' _ '{}' \;

Maybe we can find out what needs to be corrected.

1. Architecture:
pol@PowerMac-G5:~$ dpkg --print-architecture
powerpc

2. Update (system reports in Dutch, but I assume that you can guess the English translation):
pol@PowerMac-G5:~$ sudo apt update
[sudo] wachtwoord voor pol:
Geraakt:1 http://ports.ubuntu.com/ubuntu-ports xenial InRelease
Ophalen:2 http://ports.ubuntu.com/ubuntu-ports xenial-updates InRelease [99,8 kB]
Ophalen:3 http://ports.ubuntu.com/ubuntu-ports xenial-backports InRelease [97,4 kB]
Geraakt:4 http://archive.canonical.com/ubuntu xenial InRelease
Ophalen:5 http://ports.ubuntu.com/ubuntu-ports xenial-security InRelease [99,8 kB]
Ophalen:6 http://ports.ubuntu.com/ubuntu-ports xenial-updates/main powerpc DEP-11 Metadata [315 kB]
Ophalen:7 http://ports.ubuntu.com/ubuntu-ports xenial-updates/universe powerpc DEP-11 Metadata [278 kB]
Ophalen:8 http://ports.ubuntu.com/ubuntu-ports xenial-updates/multiverse powerpc DEP-11 Metadata [4.068 B]
Ophalen:9 http://ports.ubuntu.com/ubuntu-ports xenial-backports/main powerpc DEP-11 Metadata [3.328 B]
Ophalen:10 http://ports.ubuntu.com/ubuntu-ports xenial-backports/universe powerpc DEP-11 Metadata [6.596 B]
Ophalen:11 http://ports.ubuntu.com/ubuntu-ports xenial-security/main powerpc DEP-11 Metadata [84,1 kB]
Ophalen:12 http://ports.ubuntu.com/ubuntu-ports xenial-security/universe powerpc DEP-11 Metadata [124 kB]
1.112 kB opgehaald in 2s (412 kB/s)
(…)
Pakketlijsten worden ingelezen... Klaar
N: Opvragen van het in de configuratie vermeld bestand 'main/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-updates InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'restricted/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-updates InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'universe/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-updates InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'multiverse/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-updates InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'main/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-backports InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'restricted/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-backports InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'universe/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-backports InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'multiverse/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-backports InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'main/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-security InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'restricted/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-security InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'universe/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-security InRelease' de architectuur 'powerpc' niet ondersteunt
N: Opvragen van het in de configuratie vermeld bestand 'multiverse/binary-powerpc/Packages' overgeslagen, vermits pakketbron 'http://ports.ubuntu.com/ubuntu-ports xenial-security InRelease' de architectuur 'powerpc' niet ondersteunt

3. Sources:
pol@PowerMac-G5:~$ find /etc/apt -name '*.list' -exec bash -c 'echo -e "\n$1\n"; cat -n "$1"' _ '{}' \;

/etc/apt/sources.list

     1 # deb cdrom:[Lubuntu 16.04 LTS _Xenial Xerus_ - Release powerpc (20160420)]/ xenial main main/dist-upgrader multiverse restricted universe
     2
     3 # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
     4 # newer versions of the distribution.
     5 deb http://ports.ubuntu.com/ubuntu-ports/ xenial main restricted
     6 # deb-src http://be.ports.ubuntu.com/ubuntu-ports/ xenial main restricted
     7
     8 ## Major bug fix updates produced after the final release of the
     9 ## distribution.
    10 deb http://ports.ubuntu.com/ubuntu-ports/ xenial-updates main restricted
    11 # deb-src http://be.ports.ubuntu.com/ubuntu-ports/ xenial-updates main restricted
    12
    13 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
    14 ## team, and may not be under a free licence. Please satisfy yourself as to
    15 ## your rights to use the software. Also, please note that software in
    16 ## universe/multiverse WILL NOT receive any review or updates from the Ubuntu security
    17 ## team.
    18 deb http://ports.ubuntu.com/ubuntu-ports/ xenial universe multiverse
    19 # deb-src http://be.ports.ubuntu.com/ubuntu-ports/ xenial universe multiverse
    20 deb http://ports.ubuntu.com/ubuntu-ports/ xenial-updates universe multiverse
    21 # deb-src http://be.ports.ubuntu.com/ubuntu-ports/ xenial-updates universe multiverse
    22
    23 ## N.B. software from this repository may not have been tested as
    24 ## extensively as that contained in the main release, although it includes
    25 ## newer versions of some applications which may provide useful features.
    26 ## Also, please note that software in backports WILL NOT receive any review
    27 ## or updates from the Ubuntu security team.
    28 deb http://ports.ubuntu.com/ubuntu-ports/ xenial-backports main restricted universe multiverse
    29 # deb-src http://be.ports.ubuntu.com/ubuntu-ports/ xenial-backports main restricted universe multiverse
    30
    31 ## Uncomment the following two lines to add software from Canonical's
    32 ## 'partner' repository.
    33 ## This software is not part of Ubuntu, but is offered by Canonical and the
    34 ## respective vendors as a service to Ubuntu users.
    35 deb http://archive.canonical.com/ubuntu xenial partner
    36 # deb-src http://archive.canonical.com/ubuntu xenial partner
    37
    38 deb http://ports.ubuntu.com/ubuntu-ports/ xenial-security main restricted
    39 # deb-src http://ports.ubuntu.com/ubuntu-ports xenial-security main restricted
    40 deb http://ports.ubuntu.com/ubuntu-ports/ xenial-security universe multiverse
    41 # deb-src http://ports.ubuntu.com/ubuntu-ports xenial-security universe multiverse

My machine can reach the repositories, but they are all skipped ("overgeslagen") because they don't support ("niet ondersteunt") the powerpc architecture. Why did Ubuntu remove these binaries and are they still available somewhere?

Other distributions support PPC. You could switch to one of those
https://www.pcwdld.com/best-powerpc-linux-distros

The error message that powerpc is no more supported comes unexpected.

Strange detail: on http://ports.ubuntu.com/dists/xenial-updates/ the Contents-powerpc.gz file is still there, but it has a date of January 2022, and not December as the other ones.

What I found is an announcement from December 2016 that states, that 32-bit PowerPC support will end
https://lists.ubuntu.com/archives/ubuntu-devel-announce/2016-December/001199.html

Apparently the decision has been taken to end all support with the EOL date of Xenial (April 2021)

There should still be a possibility to install the newer (4.4.0-210 version) of the kernel manually.
Either you have the *.deb packages on your other machine, or you can search for them on the Launchpad servers.

@Manfred:
The header of the file "inRelease" in the "Xenial" dist mentions powerpc:

Origin: Ubuntu
Label: Ubuntu
Suite: xenial
Version: 16.04
Codename: xenial
Date: Thu, 21 Apr 2016 23:23:46 UTC
Architectures: amd64 arm64 armhf i386 powerpc ppc64el s390x
Components: main restricted universe multiverse
Description: Ubuntu Xenial 16.04

But the header of the file "InRelease" in the "Xenial/updates" dist does not:

Origin: Ubuntu
Label: Ubuntu
Suite: xenial-updates
Version: 16.04
Codename: xenial
Date: Wed, 28 Dec 2022 16:57:34 UTC
Architectures: amd64 arm64 armhf i386 ppc64el s390x
Components: main restricted universe multiverse
Description: Ubuntu Xenial Updates

That may possibly explain the error message. Is this a (recent) bug or was it intentionally done?
And if so, is there somewhere on this world a server that still offers Xenial-updates?
Manual updates are not an option for me; my focus is Linux From Scratch, not Ubuntu.

@Andrew:
yes, there are maybe other distros with support for powerpc, and I may try them sometime.
But I am very surprised that Ubuntu made the Xenial-updates unreachable, I don't see a good reason for this.
So I am wondering if something is wrong with my setup or if there is a work-around for that strange decision.

The updates were removed because the release is not supported,so why keep the packages. Microsoft doesn't keep updates for Windows 98 either.... It's the same thing.

Nothing wrong at all. You are using a dead release of Ubuntu which is not supported and should be used by nobody. Makes total sense to remove the packages from the servers to save s resources.

If you are not running Ubuntu, but something else, then you are wrong here.
Support for Linux from scratch can be found at https://www.linuxfromscratch.org/support.html

@Andrew:
I don't understand the decision of Ubuntu: why only removing Xenial-updates and keeping Xenial? What savings can you realise by deleting a few GB of data?

Microsoft is a bad example. I am an Apple adept; I can still install and update macos on a 20-years old Apple computer form the Apple servers. I can even download the operating system ProDos from the eighties (although not from Apple).

I am indeed using a dead release of Ubuntu for my PowerMac G3 - G4 - G5. The last Xenial updates were released around early 2021, so not bad at all. Why is now only the first release (2016) left?

@Manfred:
I do run Ubuntu. I use it as host distro to build the latest LFS on 20-year old PowerMacs (yes that's possible…). But there are a number of requirements for the host system to build LFS (like a fairly recent gcc). That's why I need an up-to-date Xenial, that's why I ask my question here, not on the LFS fora.

Anyway, asked a question got some answers. My problem is not solved and the outcome is that there is most probably no solution. Thanks for the time you took to look into it.

I agree with you that it is strange, that the powerpc repository for xenial is still working, just for xenial-updates it isn't.

"Manual updates are not an option for me; my focus is Linux From Scratch, not Ubuntu."

I do not understand the justification in this sentence. What prevents doing a manual update?

About manual updates: I am afraid that it will take too much time. Especially to discover and fullfill all the dependencies. Ubuntu is just a tool for me. The real fun is to build the latest LFS on an old PowerMac.

Just as an example: I tried many things to solve the upgrade problem, amongst others installing another set of programs with tasksel (Samba file server + Ubuntu desktop + OpenSSH server + Basic Ubuntu server). The result is that the window manager is broken (I have a blank screen with a mouse pointer) and that "sudo apt update" generates an exception (but still seems to work). I am afraid that I may break more things with a manual upgrade.

And my frustration is that everything worked perfect untill about one year ago.
Is this intentionally done by Ubuntu to push more users to their ESM program?

BTW: another thing I tried is installing the "Ubuntu kernel lifecycle and enablement stack" (https://ubuntu.com/kernel/lifecycle#installation-16-04). But the installation command is unknown to my Ubuntu version.

What exactly do you need, that is only in xenial-update but not in xenial?

I cannot imagine that it makes a difference for compiling "Linux from scratch" whether you have the 4.4.0-210.242 or the 4.4.0-21.37 version of the kernel.

And for ESM: please read https://ubuntu.com/security/esm (below the Heading "What's covered")
It shows that ESM is not available for PowerPC architecture on Ubuntu 16.04.

There is a list with minimal requirements (not only for the kernel, but also for a number of tools like gcc) to build an LFS and I have to admit that the base version of Xenial fullfills it.

But I find it strange that somethings that was working perfectly about one year ago, is intentionally (?) not available anymore and I see no good reason for that. That's the reason why I am asking about it on this forum.

But there is more:
1. I got a message at login that a new release is available (18.04 LTS or higher). That's not correct for a powerpc;
2. I tried the dist-upgrade and it broke my Xenial (after a failing roll-back);
3. I also got a message about ESM in case a dist-upgrade is not an option. You now tell me that this is again not correct for a powerpc.
That's a lot of bad points for Ubuntu…