Hi, I'm trying to run pants with python 3.13 and I'm getting the error

ProcessExecutionFailure: Process 'Find interpreter for constraints: CPython==3.13.*' failed with exit code 1.
stdout:

stderr:
No supported version of Pip is compatible with the given targets
...

do I need to fix or otherwise specify a version/version range for pip or is this a symptom of something else?

What version of Pants are you running?

2.22.0

Gotcha. You may need to update the version of PEX in your

pants.toml

to the latest version - that should support the latest Pip + Python 3.13: https://www.pantsbuild.org/2.21/reference/subsystems/pex-cli

It looks like actually it might be a

PATH

issue, when I run

pants lint

even when specifying 3.12 instead, I get the same error but it mentions all installed versions of python on my system. I'm wondering if the 3.13 install could have done something more than just add the latest version to the

PATH

🤦 any ideas would be great, I think the issue I'm having is getting in the way before I even get to the issue you mention!

Can you paste in the error that you get when trying to run

pants lint

with 3.12?

Sure, here it is:

Engine traceback:
  in `lint` goal

ProcessExecutionFailure: Process 'Find interpreter for constraints: CPython<4,>=3.7' failed with exit code 1.
stdout:

stderr:
No supported version of Pip is compatible with the given targets:
cp310-cp310-macosx_14_0_arm64 interpreter at /Library/Frameworks/Python.framework/Versions/3.10/bin/python3.10
cp311-cp311-macosx_14_0_arm64 interpreter at /Library/Frameworks/Python.framework/Versions/3.11/bin/python3.11
cp312-cp312-macosx_14_0_arm64 interpreter at /Users/mkahan/Development/vonage-python-sdk/venv-edit/bin/python3.12
cp313-cp313-macosx_14_0_arm64 interpreter at /Library/Frameworks/Python.framework/Versions/3.13/bin/python3.13
cp37-cp37m-macosx_14_0_x86_64 interpreter at /Library/Frameworks/Python.framework/Versions/3.7/bin/python3.7
cp39-cp39-macosx_14_0_arm64 interpreter at /Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.9/bin/python3.9

Hmm yeah, I think this has to do with your interpreter constraints; there is no version of Pip that is compatible with both Python 3.7 and 3.13. See here for more details: https://github.com/pantsbuild/pants/issues/21103 Try setting your upper bound to 3.12 instead, and seeing if that works, so:

CPython<=3.12,>=3.7

My interpreter constraints looks like this:

[python]
interpreter_constraints = ['==3.12.*']

Hmm, is that being overridden somewhere? Because the output contains:

Process 'Find interpreter for constraints: CPython<4,>=3.7' failed with exit code 1.

Not that I can see, no....

What does your lockfile say? It should contain something like this at the top:

// This lockfile was autogenerated by Pants. To regenerate, run:
//
//    pants generate-lockfiles --resolve=python-default
//
// --- BEGIN PANTS LOCKFILE METADATA: DO NOT EDIT OR REMOVE ---
// {
//   "version": 3,
//   "valid_for_interpreter_constraints": [
//     "CPython<3.13,>=3.12"
//   ],

I don't have a lockfile generated for my monorepo, running the command in yours produces no output

Okay. And what tool are you trying to run with the

pants lint

command?

autoflake, black, isort, docformatter and taplo. I think it fails when it hits docformatter

13:31:32.19 [INFO] Completed: Format with taplo - taplo made no changes.
13:31:32.20 [INFO] Canceled: Building docformatter.pex from <resource://pants.backend.python.lint.docformatter/docformatter.lock>
13:31:33.40 [ERROR] 1 Exception encountered:

You may want to set the interpreter constraints for docformatter then: https://www.pantsbuild.org/stable/reference/subsystems/docformatter#interpreter_constraints That same option is available for autoflake, black, and isort as well (but not taplo)

This was all working perfectly until I installed Python 3.13 today, it would be good to understand what might have been changed

Probably https://pantsbuild.slack.com/archives/C046T6T9U/p1728390186031419?thread_ts=1728386679.902609&cid=C046T6T9U. You only had Python 3.7-3.12 installed before that, so Pip was able to support all Pythons in that range just fine. Now that you installed 3.13 you’ll need to set a minimum of 3.8 for all tools to make Pip work nicely, as Pip cannot support both 3.7 and 3.13 at once. It sounds like you don’t need 3.7 support anyway, so I would recommend using a constraint of

>=3.8

for most of the tools.

I set all the tools to have constraints >=3.12, and I still get this error:

ProcessExecutionFailure: Process 'Find interpreter for constraints: CPython>=3.12' failed with exit code 1.
stdout:

stderr:
No supported version of Pip is compatible with the given targets:
cp312-cp312-macosx_14_0_arm64 interpreter at /Users/mkahan/Development/venv-edit/bin/python3.12
cp313-cp313-macosx_14_0_arm64 interpreter at /Library/Frameworks/Python.framework/Versions/3.13/bin/python3.13

Now, you will probably need to upgrade the PEX version as I mentioned in the OP - you can bump to the version used in Pants 2.23: https://www.pantsbuild.org/prerelease/reference/subsystems/pex-cli

I tried it and got

UnsupportedVersion: The option [pex-cli].version is set to >=2.16.2, which is not compatible with what this release of Pants expects: pex<3.0,>=2.3.0. Please update the version to a supported value, or consider using a different Pants release if you cannot change the version. Alternatively, update [pex-cli].use_unsupported_version to be 'warning'.

You have to set that to a specific version, not a range specifier: https://www.pantsbuild.org/prerelease/reference/subsystems/pex-cli#version

Oh my bad, I'll try that

I would recommend reading through the docs for all of the

[pex-cli]

options before trying to set them

Will do that now

Right, you’ll need to override the

known_versions

as well so that it contains the version and hash for the platform that you’re trying to use. PEX 2.16.2's values can be found here: https://www.pantsbuild.org/prerelease/reference/subsystems/pex-cli#known_versions

I copied the values and it's still unable to find it!

UnknownVersion: No known version of pex 2.16.2 for macos_arm64 found in ('v2.16.2|macos_arm64|f2ec29dda754c71a8b662e3b4a9071aef269a9991ae920666567669472dcd556|4284448', 'v2.16.2|macos_x86_64|f2ec29dda754c71a8b662e3b4a9071aef269a9991ae920666567669472dcd556|4284448', 'v2.16.2|linux_x86_64|f2ec29dda754c71a8b662e3b4a9071aef269a9991ae920666567669472dcd556|4284448', 'v2.16.2|linux_arm64|f2ec29dda754c71a8b662e3b4a9071aef269a9991ae920666567669472dcd556|4284448')

Try including the

v

in the version name

So when I run this with v3.12, it fixes the behaviour! Thanks, that gets me back to being able to develop. Though when I set the interpreter constraints to 3.13, I still get

The Pip requested was pip==24.0 but it does not work with the interpreter selected which is CPython 3.13.0 at /Library/Frameworks/Python.framework/Versions/3.13/bin/python3.13. Pip 24.0 requires Python <3.13,>=3.7.

What's requesting that pip version?

I believe Pants does, you can override that to 24.2 (the version supporting Python 3.13) here: https://www.pantsbuild.org/prerelease/reference/subsystems/python#pip_version

I think that the original issue would have been my interpreter constraints for the

coverage-py

tool being >=3.8, so it was implicitly covering a version range including 3.13

No, that actually was fine - the issue is only when you try to cover 3.7 and 3.13 together. The error message you got was because the default version range for most tools used to be

>=3.7, <4

(we fixed this in Pants 2.24)

I tried to set

pip_version = 'latest'

but that didn't work. I tried

pip_version = '24.2'

explicitly but still got the error:

The Pip requested was pip==24.0 but it does not work with the interpreter selected which is CPython 3.13.0 at /Library/Frameworks/Python.framework/Versions/3.13/bin/python3.13. Pip 24.0 requires Python <3.13,>=3.7.

PEX added support for Pip 24.2 in release 2.13.0: https://github.com/pex-tool/pex/releases/tag/v2.13.0 So PEX 2.16.2 should definitely support it as well. Are you sure you set

pip_version = '24.2'

in the right section of the config?

It's under the python section:

[python]
interpreter_constraints = ['==3.13.*']
pip_version = '24.2'

Hmm okay, that seems all right. Not sure why it’s still using 24.0 for you

I could upgrade to 2.23 but I guess that's the same PEX version so would require the same pip?

Yeah, I don’t think you’d gain much benefit from upgrading to 2.23, most of the changes that address this specific issue are in 2.24, ex: https://github.com/pantsbuild/pants/pull/21400

I upgraded to 2.24.0dev0 and tests worked, as did most of the linting, but

docformatter

had an error

ModuleNotFoundError: No module named 'lib2to3'

I assume it's not stable yet so not really possible for me to use python 3.13 just yet?

I haven’t tried using Python 3.13 yet, and it looks like that particular dependency (part of the standard library) was removed in 3.13: https://github.com/python/cpython/issues/104780

Yep, seems very reasonable. I'll definitely keep that in mind.

All good! Glad to be of help

Adding on to this thread - I faced the same issue today. • My pants.toml had

interpreter_constraints = ["CPython==3.11.*"]

and

pants_version = "2.21.0"

• Got python 3.13 installed automatically while running a humble

brew upgrade

(iirc,

isort

added that as dependency) • The entire thing wrecked havoc. • Simple forced uninstall of python3.13 fixed the issue right back. • If I understand correctly, ideally I should not have faced this with a hard constraint on 3.11.*

If I understand correctly, ideally I should not have faced this with a hard constraint on 3.11.*

The real issue is the tool lockfiles, which used to have constraints of `>=3.7,<4`: https://pantsbuild.slack.com/archives/C046T6T9U/p1728392666402449?thread_ts=1728386679.902609&amp;cid=C046T6T9U. You Even though you have 3.11 set in your interpreter constraints, I believe what’s happening here might be that the tool is run with Python 3.13 due to the constraints in the lockfile. Depending on what tool you try to run, you should be able to set its

interpreter_constraints

as well (ex: for Black) to avoid this issue.

I had the exact same problem today. My pants.toml file specifically locks pants to 2.20.0 and python to 3.10.12. The fix was: brew uninstall python@3.13 - which I installed by running brew upgrade