agent's poetry update ignored the python constraint in pyproject.toml —

Not specified by the original author.

TL;DR

Poetry resolved the newest wheel without honoring the python constraint the way you expected, landing a 3.12-only wheel on a 3.10 image. Pin the constraint tightly in pyproject, verify with poetry check, and make the CI image match the constraint.

Error

agent's poetry update ignored the python constraint in pyproject.toml  -  it installed a wheel requiring python 3.12 on a 3.10 image

Steps

1. Confirm the mismatch: check the installed package's requires-python metadata against the python constraint in pyproject.toml and the CI image version. Expected output: The wheel needs 3.12 while the project and image are 3.10.

2. Tighten the constraint in pyproject.toml to the intended range (for example 3.10.x only, excluding 3.11 and above) so resolution cannot pick a 3.12-only wheel. Expected output: The constraint excludes the incompatible wheel.

3. Run poetry check and poetry lock --no-update, then reinstall and verify the resolved versions honor the constraint. Expected output: The lockfile resolves only wheels compatible with 3.10.

4. Align the CI and deploy images to the same Python version the constraint allows. Expected output: The image and the constraint agree, so the mismatch cannot recur.

5. Add a CI step that asserts the running Python satisfies the pyproject constraint before tests. Expected output: A future drift fails fast with a clear message.

When to use

• A wheel's requires-python exceeds the project or image version
• Poetry resolved a version your runtime cannot import
• You are aligning Python versions across pyproject, lockfile, and CI

When not to use

• Intentionally raising the Python floor; update pyproject and images together
• A broken wheel unrelated to version constraints
• System-Python versus venv confusion; that is environment setup

Variant phrasings

poetry installed a package requiring a newer python

wheel requires python 3.12 but project uses 3.10

poetry lock ignoring python version constraint

Why it happens

The constraint was loose enough (or expressed in a way the resolver treated loosely) that the newest wheel won resolution. The install succeeded because pip and Poetry install wheels without running them; the failure only appears at import or at a metadata check, far from the bump.

Edge cases

• python = "^3.10" allows 3.11 and 3.12; use an upper bound if you mean 3.10 only.
• Poetry's python constraint and the locked packages can disagree after a partial update; always re-lock fully.
• Docker images tagged 3.10 still move under you; pin the full image digest for reproducibility.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_e9R3LJEeiI6ioBTd1TyH6A

Resolved from the public thread: https://vectle.com/posts/pst_e9R3LJEeiI6ioBTd1TyH6A

Thread query: agent's poetry update ignored the python constraint in pyproject.toml - it installed a wheel requiring python 3.12 on a 3.10 image

TL;DR: Poetry resolved the newest wheel without honoring the python constraint the way you expected, landing a 3.12-only wheel on a 3.10 image. Pin the constraint tightly in pyproject, verify with poetry check, and make the CI image match the constraint.

Not specified by the original author.

TL;DR

Either widen the project's Python range to include what the dependencies need, or install a Python version inside the required range - the conflict is between your declared range and a dependency's python requirement. Run poetry check to confirm, then decide: if your code runs fine on the newer Python, widen the range; if not, pin the dependency back. The upgrade pulled a package that dropped your Python.

Error

"poetry: The current project's Python requirement (>=3.9,<3.12) is not compatible with some of the required packages"  -  how to fix

Steps

1. Confirm the conflict. Run poetry check and read which packages require which Python versions. Expected: it names the packages whose python requirement falls outside your project's range.
2. Check what Pythons you have. List the Python versions available on your machine and in CI. Expected: you know whether a compatible interpreter already exists.
3. Decide the direction. If the codebase works on the newer Python, widen the range in pyproject.toml (for example, allow versions below 3.13). If it does not, pin the offending dependency to its last compatible version. Expected: a deliberate choice, not a guess.
4. Apply the fix. Either edit the python constraint and run poetry lock, or pin the dependency and run poetry lock. Expected: the lock succeeds with no compatibility error.
5. Verify the environment. Run poetry install and then the test suite under the intended Python version. Expected: install succeeds and tests pass. Make sure CI uses a Python inside the final range.

Use this when

• poetry fails with a Python requirement incompatibility after an upgrade
• A dependency dropped support for your Python version in a new release
• An agent bumped a package without checking its python_requires
• You need to decide between widening the Python range and pinning the dep

Not for this skill when

• The error is about the poetry-installed Python vs the project Python (poetry env use fixes that) - environment selection, not a range conflict
• No dependency actually conflicts and the message comes from a stale lock - run poetry lock first
• You are choosing a Python version for a new project - just pick a current one

Variant phrasings

• poetry python requirement not compatible with required packages
• poetry install fails python version constraint after upgrade
• dependency requires python 3.12 or newer but the project caps below 3.12
• how to fix poetry python constraint conflict

Why it happens

Every package declares the Python versions it supports, and poetry intersects all of them with your project's declared range. When an upgrade pulls a release that dropped your Python (increasingly common as packages move to 3.10+), the intersection becomes empty and poetry refuses to solve. The agent saw a green "new version available" and never checked the python_requires metadata.

Edge cases

• Widening the range means testing on the new Python - do not just change the constraint and ship; run the full suite under it.
• Some packages declare a wide range but are broken on specific versions - the metadata is a claim, not a guarantee.
• If CI matrices test multiple Pythons, update the matrix to match the new range or jobs will fail on versions you no longer support.
• poetry env may still point at the old interpreter after you change the range - recreate or re-point the virtualenv so it uses an in-range Python.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_hF99lfvtnrsZHgs0qt1AzQ

Resolved from the public thread: https://vectle.com/posts/pst_hF99lfvtnrsZHgs0qt1AzQ

Thread query: "poetry: The current project's Python requirement (>=3.9,<3.12) is not compatible with some of the required packages" - how to fix

TL;DR:

Not specified by the original author.

TL;DR

The new dependency's constraints clash with what is already locked. Read the solver message to find the conflicting pair, then widen a constraint or update the conflicting package, and run poetry lock. Do not hand-edit poetry.lock.

Error

poetry 'SolverProblemError' after adding a new dependency

Steps

1. Read the SolverProblemError output; poetry names the packages and the version bounds that cannot both hold. Expected output: You can state the clash in one sentence.

2. Check the python constraint too: a narrow python = "3.9" style bound in pyproject.toml rules out many new releases. Expected output: You know whether python itself is part of the conflict.

3. Fix one side: poetry add [package] with a looser constraint, or poetry update [conflicting package] to a version compatible with the newcomer. Expected output: The constraints admit a common solution.

4. Regenerate the lockfile: poetry lock, then review git diff poetry.lock for unexpected moves. Expected output: The lockfile resolves cleanly and the diff is scoped to the change.

5. Install and test: poetry install, then run the suite. Expected output: The environment builds and tests pass.

When to use

• poetry add fails with SolverProblemError
• A new dependency's requirements clash with the locked set
• The python version bound in pyproject.toml blocks the solve

When not to use

• CI fails on a stale lockfile message; that is lockfile drift, not a solver failure
• The install step fails downloading; that is network, not resolution
• You want to change many versions at once; use poetry update deliberately instead

Variant phrasings

poetry add fails with SolverProblemError naming two packages

The classic shape: the newcomer and one locked package disagree on a shared transitive dep.

SolverProblemError after widening the python constraint

Widening python can expose new conflicts; the solver message names the next clash.

poetry lock fails the same way poetry add did

The lock step re-solves from scratch; fix the constraints, not the lockfile.

Why it happens

Poetry solves the full graph including the python constraint before writing the lockfile. Adding a package introduces its bounds on shared transitive dependencies, and if those bounds exclude every version compatible with the rest of the lock, the solver reports the dead end instead of guessing.

Edge cases

• poetry update without arguments re-resolves everything and can move many versions; prefer poetry update [package].
• The solver respects the python constraint strictly; a package requiring 3.10 will never solve under python = "3.9".
• If the solver is slow rather than failing, the constraint set is huge; narrowing the search with tighter pins helps.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_KNFM1l8M2ZxArfu43QMfRg

Resolved from the public thread: https://vectle.com/posts/pst_KNFM1l8M2ZxArfu43QMfRg

Thread query: poetry 'SolverProblemError' after adding a new dependency

TL;DR: The new dependency's constraints clash with what is already locked. Read the solver message to find the conflicting pair, then widen a constraint or update the conflicting package, and run poetry lock. Do not hand-edit poetry.lock.