pip resolver error: "pip's dependency resolver does not currently take into account all the packages that are...

TL;DR

The message means your environment has packages pip did not choose and cannot reconcile - find the conflict with pip check, then pin or upgrade the disagreeing packages so the resolver sees one consistent set. This warning shows up when something (an agent, a manual install, a --no-deps upgrade) put the environment in a state the resolver cannot reproduce. Read which constraint is actually violated instead of upgrading blindly.

Error

pip resolver error: "pip's dependency resolver does not currently take into account all the packages that are installed" after an upgrade

Steps

1. See the broken state. Run pip check. Expected: it lists packages with incompatible requirements, e.g. "package-a 2.0 requires package-b below 3, but you have package-b 3.1".
2. Find who installed the odd one out. Think about what changed: a recent upgrade, a --no-deps install, or an agent editing requirements. Expected: you identify the install step that created the inconsistency.
3. Reproduce the conflict in the resolver. Run the upgrade again and read the "The conflict is caused by" section of the error. Expected: pip names the exact packages and version constraints that disagree.
4. Fix the constraint set. Either pin the upgraded package to a version compatible with the rest, or upgrade the conflicting packages together so all constraints are satisfiable. Expected: the requirement set has no contradictions.
5. Verify clean. Run pip check again. Expected: it prints "No broken requirements found." Then re-run the original install command and confirm the warning is gone.

Use this when

• pip prints the "does not currently take into account" message after an upgrade
• pip check reports broken or incompatible requirements
• An agent upgraded one package and left the environment inconsistent
• You need to read which constraint actually conflicts in a ResolutionImpossible-style failure

Not for this skill when

• The error is a hard ResolutionImpossible with no installed packages involved - read the conflict section directly
• Packages were installed with --no-deps on purpose and you manage deps manually - the warning is expected
• The environment is a deliberate mix (e.g. testing against multiple versions) - use separate virtualenvs instead

Variant phrasings

• pip dependency resolver ignoring installed packages
• pip check shows broken requirements after upgrade
• pip resolver warning after pip install --upgrade
• inconsistent environment after automated pip upgrade

Why it happens

pip's resolver starts from the requirements you give it and the packages it can see, but it does not fully account for every already-installed package - especially ones installed outside the resolver (with --no-deps, by hand, or by an agent editing site-packages indirectly). After such an install, the environment contains a combination the resolver would never have produced, and it warns you that its view of the world is incomplete.

Edge cases

• Upgrading with pip install --upgrade [pkg] alone often creates this: it bumps one package without re-resolving its dependents - upgrade the dependents in the same command.
• If the conflict involves a package with no compatible version combination, you need a constraints file to force the set, not more upgrading.
• Never "fix" this by uninstalling the complaining package without understanding the chain - something depends on it.
• In CI, build the environment from a locked requirements file instead of upgrading in place; in-place upgrades are where this warning is born.

Provenance

Resolved from the public thread: https://vectle.com/posts/psteA0s-ztZvZ9AIhlZeLyJw