pipx + uv backend is broken

[florianhumblot]

When a tool uses the pipx-backend, and pipx uses uv, it passes a flag that is unknown to uv.
i.e. if I try to mise install azure-cli I get :

DEBUG ARGS: C:\Users\<redacted>\AppData\Local\Microsoft\WinGet\Packages\jdx.mise_Microsoft.Winget.Source_8wekyb3d8bbwe\mise\bin\mise.exe install --verbose
DEBUG [vfox] Getting metadata for yarn
DEBUG config: C:\Users\<redacted>\RustRoverProjects\<redacted>\mise.toml
DEBUG config: C:\Users\<redacted>\.config\mise\config.toml
DEBUG Pipx registry URL: https://pypi.org/pypi/{}/json
DEBUG Fetching JSON for azure-cli
DEBUG GET https://pypi.org/pypi/azure-cli/json
DEBUG GET https://pypi.org/pypi/azure-cli/json 200 OK
INFO  pipx:azure-cli@2.87.0 [1/3] install
INFO  pipx:azure-cli@2.87.0 [1/3] pipx install azure-cli==2.87.0
DEBUG Converted registry URL to index URL: https://pypi.org/simple
DEBUG $ pipx install azure-cli==2.87.0 --pip-args=--uploaded-prior-to=2026-06-15T11:29:11.5476527Z
creating virtual environment...
installing azure-cli from spec 'azure-cli==2.87.0'...
Fatal error from uv prevented installation. Full uv output in file:
    C:\Users\<redacted>\AppData\Local\mise\installs\pipx-azure-cli\2.87.0\logs\cmd_2026-06-16_13.29.12_uv_errors.log
Error installing azure-cli from spec 'azure-cli==2.87.0'.
ERROR pipx failed
DEBUG [vfox] Getting metadata for yarn
DEBUG config: C:\Users\<redacted>\RustRoverProjects\<redacted>\mise.toml
DEBUG config: C:\Users\<redacted>\.config\mise\config.toml
Error:
   0: Failed to install pipx:azure-cli@latest: pipx exited with non-zero status: exit code 1

Location:
   src\toolset\toolset_install.rs:244

Version:
   2026.6.10 windows-x64 (2026-06-14)

Backtrace omitted. Run with RUST_BACKTRACE=1 environment variable to display it.
Run with RUST_BACKTRACE=full to include source snippets.

The file it mentions C:\Users\<redacted>\AppData\Local\mise\installs\pipx-azure-cli\2.87.0\logs\cmd_2026-06-16_13.29.12_uv_errors.log doesn't actually exist.

If I try to do the tool-invocation manually, i.e. pipx install azure-cli==2.87.0 --pip-args=--uploaded-prior-to=2026-06-15T11:29:11.5476527Z that also fails with the following error:

⣷ installing azure-cli from spec 'azure-cli==2.87.0'Fatal error from uv prevented installation. Full uv output in file:
    C:\Users\<redacted>\pipx\logs\cmd_2026-06-16_13.27.14_uv_errors.log

Error installing azure-cli from spec 'azure-cli==2.87.0'.

And this time the log file does exit, and contains:

UV STDOUT
----------

UV STDERR
----------
error: unexpected argument '--uploaded-prior-to' found

  tip: a similar argument exists: '--upgrade-group'

Usage: uv.exe pip install --python <PYTHON> --quiet... --upgrade-group <UPGRADE_GROUP> <PACKAGE|--requirements <REQUIREMENTS>|--editable <EDITABLE>|--group <GROUP>>

For more information, try '--help'.

So there seem to be two issues:

1. pipx is passing the wrong argument to uv
2. mise is not passing the correct path for logging

[johnseekins]

I'm getting a similar error with pipx passing that switch to pip:

upgrading shared libraries...
Usage:   
  ~/.local/share/mise/installs/yamllint/1.38.0/shared/bin/python -m pip install [options] <requirement specifier> [package-index-options] ...
  ~/.local/share/mise/installs/yamllint/1.38.0/shared/bin/python -m pip install [options] -r <requirements file> [package-index-options] ...
  ~/.local/share/mise/installs/yamllint/1.38.0/shared/bin/python -m pip install [options] [-e] <vcs project url> ...
  ~/.local/share/mise/installs/yamllint/1.38.0/shared/bin/python -m pip install [options] [-e] <local project path> ...
  ~/.local/share/mise/installs/yamllint/1.38.0/shared/bin/python -m pip install [options] <archive url/path> ...
no such option: --uploaded-prior-to
Failed to upgrade shared libraries
'~/.local/share/mise/installs/yamllint/1.38.0/shared/bin/python -m
pip --no-input --disable-pip-version-check install --upgrade
--uploaded-prior-to=2026-06-15T15:48:07.61659432Z --force-reinstall -q pip >=
23.1' failed

Which is interesting, 'cause pip definitely supports --uploaded-prior-to:

$ pip install --help | grep prior
  --uploaded-prior-to <datetime_or_duration>
                              Only consider packages uploaded prior to the
$ pip -V
pip 26.1.2 from ~/.local/share/mise/installs/python/3.13.14/lib/python3.13/site-packages/pip (python 3.13)

[johnseekins]

This particular error looks like a bit of a chicken/egg problem:

An initial version of pip old enough to not support --uploaded-prior-to crashes while we try to update to a version that does support the flag...

[johnseekins]

This PR maybe solves the issue?
#10490
But I'm very new to rust (and mise) development, so I'm 100% certain it is right or useful.

[risu729]

Thanks for the PR, but I think we shouldn't silently drop the flags. I already had a PR in #10472, so I'll work on it.

[johnseekins]

Yeah. Yours is better. Thanks for working on this.

[risu729]

I didn't know pipx started suppoting uv. I'll have a look

[coreone]

I ran into a similar issue today, and it looks like the error started in version 2026.6.2. If I run my workflow with 2026.6.1 or before, everything with pipx works as expected.

[coreone]

As a follow up to this, this seems to be an issue with pipx using the available pip by default. In GitHub Actions, if I just run the jdx/mise-action action in a workflow, it fails with the referenced error. However, if I do an actions/setup-python for something like 3.14, the workflow succeeds as that (today) installs pip@26.1.2. This is because the available pip in a generic Action (today) is 24.0, but version 26 or greater is needed for the --uploaded-prior-to flag used with the pipx backend. I solved this in my workflow by adding python = "3.14" to mise.toml, which makes the newer pip version available. I believe this should work for environments outside GitHub Actions, however, this doesn't feel like a full solution for this issue.

[risu729]

Yes, #10472 should fix that