Call for testing: Snapcraft 9.0

mr_cal · May 8, 2026, 11:25am

On behalf of the Starcraft team, I’m pleased to announce that Snapcraft 9.0 is available in the latest/candidate and 9.x/candidate channels. The tentative release date for the stable channel is 2026-05-19T05:00:00Z.

The major changes in Snapcraft 9 are support for core26 and the removal of core20. Users who still need to build core20 snaps should remain on the 8.x channel.

Compared to the transitions to Snapcraft 7 and 8, this release includes far fewer internal refactorings. As a result, we expect the migration from core24 to core26 to be relatively straightforward for most projects. One important exception is the the removal of Python from the core26 snap.

For a complete overview of the changes in Snapcraft 9, see the release notes.

If you have any feedback or issues, please report them here or open an issue.

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dilyn · May 8, 2026, 5:36pm

Good work, team I look forward to parallel installing a fifth snapcraft.

sdeziel · May 9, 2026, 8:41pm

When building from this core26 branch with snapcraft 9.0, I get the following:

$ snapcraft clean && time snapcraft pack
Version has been set to '0+git.3660b5d'
Version has been set to '0+git.3660b5d'
Lint warnings:
- library: bin/ovn-nbctl: missing dependency 'libunbound.so.8'. (https://documentation.ubuntu.com/snapcraft/stable/how-to/debugging/use-the-library-linter)
- library: bin/ovn-sbctl: missing dependency 'libunbound.so.8'. (https://documentation.ubuntu.com/snapcraft/stable/how-to/debugging/use-the-library-linter)
- library: bin/ovs-vsctl: missing dependency 'libunbound.so.8'. (https://documentation.ubuntu.com/snapcraft/stable/how-to/debugging/use-the-library-linter)
Version has been set to '0+git.3660b5d'
Packed lxd_0+git.3660b5d_amd64.snap

real	27m9.451s
user	0m7.595s
sys	0m3.439s

And the libunbound.so is indeed missing from the resulting snap. When building with the older snapcraft, the lib is properly primed and there is no linter warning either.

$ snap list --all snapcraft 
Name       Version  Rev    Tracking          Publisher   Notes
snapcraft  8.14.5   17634  latest/candidate  canonical✓  classic
snapcraft  9.0.0    18124  latest/candidate  canonical✓  disabled,classic

dilyn · May 11, 2026, 2:33pm

Is libunbound8 in any of the {parts,stage,prime}/ directories? What plugin is the part which should be staging this using?

I had a similar sort of problem with libmalloc not being unpacked into $CRAFT_PART_INSTALL which I still haven’t resolved, maybe they’re related…

mr_cal · May 11, 2026, 3:21pm

@dilyn, let me know if you can make a small reproducer or get more information.

@sdeziel, this is almost certainly a new bug in Snapcraft 9. Core26 switched to a chiseled base, so craft-parts gained support for parsing chisel manifests. This is used for determining the stage-package cutoff. It’s certainly not working as-intended in Snapcraft.

I see the core26 added wall2dpkg a few days ago, which may be an easy path forward for Snapcraft. I’ll need to root cause the current failure first.

@sdeziel, can you submit an issue in snapcraft so we can prioritize it?

sdeziel · May 11, 2026, 5:08pm

@mr_cal snapcraft 9.0 doesn't prime files in the same way 8.x did · Issue #6248 · canonical/snapcraft · GitHub Thanks for looking into this!

mr_cal · May 11, 2026, 5:40pm

Thanks! It seems Snapcraft is working as expected (believe it or not), I followed up in the github issue with an upstream issue for core26.

TehAppKiller · May 11, 2026, 5:58pm

Same dependencies problem with python.

  test:
    plugin: nil
    source: .
    stage-packages:
      - python3

with core26

with Snapcraft 8

Fetching stage-packages
Downloading package: python3.14
Downloading package: libffi8
Downloading package: netbase
Downloading package: readline-common
Downloading package: gcc-16-base
Downloading package: libtinfo6
Downloading package: tzdata
Downloading package: python3-minimal
Downloading package: liblzma5
Downloading package: libexpat1
Downloading package: libpython3.14-minimal
Downloading package: debconf
Downloading package: openssl-provider-legacy
Downloading package: libc-gconv-modules-extra
Downloading package: libreadline8t64
Downloading package: libdb5.3t64
Downloading package: python3
Downloading package: libzstd1
Downloading package: libc6
Downloading package: libuuid1
Downloading package: media-types
Downloading package: libpython3.14-stdlib
Downloading package: libsqlite3-0
Downloading package: libpython3-stdlib
Downloading package: libssl3t64
Downloading package: libncursesw6
Downloading package: libbz2-1.0
Downloading package: python3.14-minimal
Downloading package: zlib1g
Downloading package: libgcc-s1

with Snapcraft 9

Fetching stage-packages
Downloading package: python3

This contradicts the statement in dedicated post that nothing has to be done for snaps using python without python plugin:

If it stays this way,

it would require:

    environment:
      PATH: $SNAP/usr/bin:$PATH

  test:
    plugin: nil
    source: .
    stage-packages:
      - python3
      - python3-minimal #required for 'python3' symlink # redundant with python3 package
      - python3.14-minimal #required for python bin # redundant with python3 and python3-minimal packages

(and wouldn’t include minimal python modules as it is the case in core24)

and wouldn’t display any warning or error during build like other linters can do, if the snap is not updated.

dilyn · May 11, 2026, 9:02pm

I think I largely figured out what’s happening, so I think the issue is mostly a documentation one.

github.com/canonical/craft-parts

uv plugin documentation is misleading

opened 09:01PM - 11 May 26 UTC

dilyn-corner

### What needs to get done The uv plugin documentation should be updated to exp…lain the consequences of using certain environment variables, and potentially their workarounds (or an example snap be made to explain how to appropriately handle uv and python). I've tested this for both core22 and core24, and both seem impacted. I think core26+ and bare are fine, as the plugin(s) handle the interpreter differently in those cases. ### Why it needs to get done As written, the uv plugin documentation does not adequately explain the impacts of using certain environment variables. This results in broken snaps due to unexpected behavior (at least, it's unexpected for me). Consider the (common) case where the snap must package its own python interpreter (due to, say, a python version requirement). In this case, one must add: ```yaml build-environment: - UV_PYTHON: "python3.xy" - PARTS_PYTHON_INTERPRETER: "python3.xy" - UV_PYTHON_PREFERENCE: "only-managed" - UV_PYTHON_DOWNLOADS: "auto" ``` This must be done to tell uv which python version to use, but also the (undocumented, at least here) `PARTS_PYTHON_INTERPRETER` must be specified as well in order for the `uv venv` command to use the correct python version and avoid errors relating to the build being unable to find the correct python in `$CRAFT_PART_INSTALL` (remove the last two lines, indeed probably your build will fail): ```bash :: + uv venv --relocatable --allow-existing --python /usr/bin/python3.10 /root/parts/my-part/install :: Using CPython 3.10.12 interpreter at: /usr/bin/python3.10 :: warning: The requested interpreter resolved to Python 3.10.12, which is incompatible with the project's Python requirement: `>=3.11, <4.0` (from `project.requires-python`) :: Creating virtual environment at: /root/parts/my-part/install :: Activate with: source /root/parts/my-part/install/bin/activate :: + PARTS_PYTHON_VENV_INTERP_PATH=/root/parts/my-part/install/bin/python3.11 :: + uv sync --no-dev --no-editable --reinstall --extra cpu :: Using CPython 3.11.0rc1 interpreter at: /root/parts/my-part/install/usr/bin/python3.11 :: Removed virtual environment at: /root/parts/my-part/install :: Creating virtual environment at: /root/parts/my-part/install :: Building immich-ml @ file:///root/parts/my-part/build/machine-learning :: × Failed to build `immich-ml @ file:///root/parts/my-part/build/machine-learning` :: ├─▶ Failed to identify base Python interpreter :: ╰─▶ failed to canonicalize path `/root/parts/my-part/install/usr/bin/python3.11`: No such file or directory (os error 2) ``` https://github.com/canonical/craft-parts/blob/0910f51749eda1416b08e8389527f81e2ef8ce9f/craft_parts/plugins/uv_plugin.py#L108 However, when this is done, the venv target directory (`$CRAFT_PART_INSTALL`) is fully cleaned. This means that any `stage-packages` for this part will be unpacked, and then removed. You can see this with the minimal part: ```yaml parts: my-part: plugin: uv source: somesource stage-packages: [hello] build-environment: - UV_PYTHON: "python3.xy" - PARTS_PYTHON_INTERPRETER: "python3.xy" - UV_PYTHON_PREFERENCE: "only-managed" - UV_PYTHON_DOWNLOADS: "auto" override-build: | exit 1 ``` And inspecting `$CRAFT_PART_INSTALL` (`snapcraft --debug`), then removing the `override-build` and checking again (you'll see that the previous contents of `$CRAFT_PART_INSTALL` no longer exist). Below is a "minimal" reproducer: ```yaml name: not-staging # you probably want to 'snapcraft register <name>' base: core22 # the base snap is the execution environment for this snap version: '0.1' # just for humans, typically '1.2+git' or '1.3.2' summary: Single-line elevator pitch for your amazing snap # 79 char long summary description: | This is my-snap's description. You have a paragraph or two to tell the most important story about your snap. Keep it under 100 words though, we live in tweetspace and your description wants to look good in the snap store. grade: devel # must be 'stable' to release into candidate/stable channels confinement: devmode # use 'strict' once you have the right plugs and slots package-repositories: - type: apt ppa: deadsnakes/ppa key-id: F23C5A6CF475977595C89F51BA6932366A755776 parts: my-part: plugin: uv source: https://github.com/immich-app/immich source-depth: 1 source-type: git source-tag: v2.7.5 source-subdir: machine-learning uv-extras: [cpu] build-snaps: [astral-uv] build-packages: [libpython3.11-dev, python3.11-dev] stage-packages: - gunicorn:all - libgl1:${CRAFT_ARCH_BUILD_FOR} - libmimalloc2.0:${CRAFT_ARCH_BUILD_FOR} - libpython3.11:${CRAFT_ARCH_BUILD_FOR} - python3.11:${CRAFT_ARCH_BUILD_FOR} - python3-minimal:${CRAFT_ARCH_BUILD_FOR} - python3.11-minimal:${CRAFT_ARCH_BUILD_FOR} build-environment: - UV_PYTHON: "python3.11" - PARTS_PYTHON_INTERPRETER: "python3.11" - UV_PYTHON_PREFERENCE: "only-managed" - UV_PYTHON_DOWNLOADS: "auto" ``` Below is a corrected version which handles everything in the anticipated manner (following snapcraft's lead): ```yaml name: not-staging # you probably want to 'snapcraft register <name>' base: core22 # the base snap is the execution environment for this snap version: '0.1' # just for humans, typically '1.2+git' or '1.3.2' summary: Single-line elevator pitch for your amazing snap # 79 char long summary description: | This is my-snap's description. You have a paragraph or two to tell the most important story about your snap. Keep it under 100 words though, we live in tweetspace and your description wants to look good in the snap store. grade: devel # must be 'stable' to release into candidate/stable channels confinement: devmode # use 'strict' once you have the right plugs and slots package-repositories: - type: apt ppa: deadsnakes/ppa key-id: F23C5A6CF475977595C89F51BA6932366A755776 parts: my-part-deps: plugin: nil stage-packages: - gunicorn:all - libgl1:${CRAFT_ARCH_BUILD_FOR} - libmimalloc2.0:${CRAFT_ARCH_BUILD_FOR} python-libs: plugin: nil stage-packages: - libpython3.11:${CRAFT_ARCH_BUILD_FOR} - python3.11:${CRAFT_ARCH_BUILD_FOR} - python3-minimal:${CRAFT_ARCH_BUILD_FOR} - python3.11-minimal:${CRAFT_ARCH_BUILD_FOR} my-part: after: [python-libs] plugin: uv source: https://github.com/immich-app/immich source-depth: 1 source-type: git source-tag: v2.7.5 source-subdir: machine-learning uv-extras: [cpu] build-snaps: [astral-uv] build-packages: [libpython3.11-dev, python3.11-dev] build-environment: - UV_PYTHON: "python3.11" - PARTS_PYTHON_INTERPRETER: "python3.11" override-build: |- craftctl default unlink "${CRAFT_PART_INSTALL}/bin/python" ln -sf python3 "${CRAFT_PART_INSTALL}/bin/python" ln -sf ../usr/bin/python3 "${CRAFT_PART_INSTALL}/bin/python3" ```

mr_cal · May 12, 2026, 7:45am

@TehAppKiller, it looks like the same bug and root cause - core26 also lists the python packages in it’s manifest.

mr_cal · May 19, 2026, 11:22am

FYI we’ll be delaying the release of Snapcraft 9.0 to stable until this issue with core26 is resolved. A fix was landed, but hasn’t been released to core26’s stable channel yet.

mr_cal · June 11, 2026, 3:49pm

Hi all,

Snapcraft 9.0 has been released to latest/stable and 9.x/stable.

picchietti · June 13, 2026, 4:40am

I’ve been able to successfully use snapcraft 9.0 stable to build my “antennas” snap. I installed it locally on Ubuntu Core 26 (on a raspberry pi 5), and everything appears to be working fine so far.

I’ll need to observe it a bit more, but core 26 appears to have also resolved a longstanding wifi firmware issue. Yay!