How does one read ResolutionImpossible error?

[ketozhang]

When pdm sync or pdm install, you may get a ResolutionImpossible error. Sometimes it may contain useful additional messages that tells you what to do. Most of the time it just prints the repr of RequirementInformation.

resolvelib.resolvers.ResolutionImpossible: 
[
  RequirementInformation(
    requirement=PythonRequirement(name='python', marker=None, extras=None, specifier=<PySpecSet >=3.7>, editable=False, prerelease=False), parent=None
  ),
  RequirementInformation(
    requirement=PythonRequirement(name='python', marker=None, extras=None, specifier=<PySpecSet >=3.8>, editable=False, prerelease=False), parent=<Candidate numpy 1.22.3 from unknown>
)]

What I can infer from this is "PDM is trying to install numpy and the candidate is numpy==1.22.3 this needs python>=3.8. Elsewhere there is a requirement for python >=3.7"

Great 👍, but where's the conflict?!

[frostming]

When you specifies python >=3.7 for your project, the python-requires from all dependencies MUST cover that range, otherwise, it leaves a hole when the user works on a particular python version. For example, when a users sees your pyproject.toml and thinks it is okay to use Python 3.7 to setup the project. However, that is not correct! numpy==1.22.3 just refused to be installed. Also please read this in documentation

[ketozhang]

Gotcha I understood that. I still stand by that I was unable to understand this by the error message alone.

[frostming]

We have already printed the hint:

Unable to find a resolution because the following dependencies don't work on all Python versions defined by the project's `requires-python`: 
    ...
To fix this, you can change the value of `requires-python` in pyproject.toml.

[ketozhang]

I wouldn't be asking this question if it did include a useful message like that. Here's a working example:

$ pipx upgrade pdm
upgraded package pdm from 2.2.1 to 2.3.2 (location: /Users/keto/.local/pipx/venvs/pdm)

$ pdm --version
PDM, version 2.3.2

$ git clone https://github.com/k4yt3x/video2x && cd video2x/

$ pdm install
Lock file version is not compatible with PDM, installation may fail
Updating the lock file...
python.use_venv is on, creating a virtualenv for this project...
Virtualenv is created successfully at /Users/keto/Projects/video2x/.venv
🔒 Lock successful
Changes are written to pdm.lock.
See /var/folders/dh/q65wqsbs3tn0993nc2j5dzy00000gn/T/pdm-install-resolve-2355rshl.log for detailed debug log.
[ResolutionImpossible]: [RequirementInformation(requirement=PythonRequirement(name='python', marker=None, extras=None, specifier=<PySpecSet >=3.7>, editable=False, prerelease=False), parent=None), RequirementInformation(requirement=PythonRequirement(name='python', marker=None,
extras=None, specifier=<PySpecSet >=3.8>, editable=False, prerelease=False), parent=<Candidate [email protected] from https://pypi.org/simple/numpy/>)]
Add '-v' to see the detailed traceback

$ cat /var/folders/dh/q65wqsbs3tn0993nc2j5dzy00000gn/T/pdm-install-resolve-2355rshl.log
pdm.termui: Error occurs
Traceback (most recent call last):
  File "/Users/keto/.local/pipx/venvs/pdm/lib/python3.10/site-packages/pdm/termui.py", line 227, in logging
    yield logger
  File "/Users/keto/.local/pipx/venvs/pdm/lib/python3.10/site-packages/pdm/cli/actions.py", line 140, in resolve_candidates_from_lockfile
    mapping, *_ = resolve(
  File "/Users/keto/.local/pipx/venvs/pdm/lib/python3.10/site-packages/pdm/resolver/core.py", line 35, in resolve
    result = resolver.resolve(requirements, max_rounds)
  File "/Users/keto/.local/pipx/venvs/pdm/lib/python3.10/site-packages/resolvelib/resolvers.py", line 521, in resolve
    state = resolution.resolve(requirements, max_rounds=max_rounds)
  File "/Users/keto/.local/pipx/venvs/pdm/lib/python3.10/site-packages/resolvelib/resolvers.py", line 414, in resolve
    raise ResolutionImpossible(self.state.backtrack_causes)
resolvelib.resolvers.ResolutionImpossible: [RequirementInformation(requirement=PythonRequirement(name='python', marker=None, extras=None, specifier=<PySpecSet >=3.7>, editable=False, prerelease=False), parent=None), RequirementInformation(requirement=PythonRequirement(name='python', marker=None, extras=None, specifier=<PySpecSet >=3.8>, editable=False, prerelease=False), parent=<Candidate [email protected] from https://pypi.org/simple/numpy/>)]

If this seems to be an issue, we can move the discussion to Issues.

[muskan1802]

i am gettion resolutionError in google colab for ISR module. How can i resolve it?? Please help

[pawamoy]

You will need to provide more information if you want someone to be able to help :)

Paste the console output, and the packages you try to install, at least.