poetry-core 1.0.5 fails to find installation candidate

• I am on the latest Poetry version.

• I have searched the issues of this repo and believe that this is not a duplicate.

• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: RHEL 7, CentOS 7, and others

• Poetry version: 1.1.4, 1.1.8, 1.1.9

Issue

Upon upgrading to poetry 1.1.9, I observed that I could no longer install a specific package in some of my projects. The package exists in two places - pypi.org, and an internal repo (running Nexus). In both places, the package is identical (i.e. same hash). Both pypi.org (as a default) and my internal repo (via configuration in pyproject.toml) is available for these projects.

When I try to install, I get the following:

  Unable to find installation candidates for kerberos (1.3.1)

  at ~/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/installation/chooser.py:72 in choose_for
       68│ 
       69│             links.append(link)
       70│ 
       71│         if not links:
    →  72│             raise RuntimeError(
       73│                 "Unable to find installation candidates for {}".format(package)
       74│             )
       75│ 
       76│         # Get the best link

The relevant parts of poetry.lock are:

[[package]]
name = "kerberos"
version = "1.3.1"
description = "Kerberos high-level interface"
category = "main"
optional = false
python-versions = "*"

[package.source]
type = "legacy"
url = "<url-to-internal-repo>"
reference = "<name-of-internal-repo>"

and

    [
        {file = "kerberos-1.3.1-cp38-cp38-macosx_10_15_x86_64.whl", hash = "md5:813b4beec4a4641d7772346d2b6485d8"},
        {file = "kerberos-1.3.1-cp39-cp39-macosx_10_9_x86_64.whl", hash = "md5:255c2409de0795669030bbc1e78ac462"},
    ]

(interestingly, in that second section, the two entries are not relevant to my platform/python version. Other entries exist on both pypi.org and my internal repo)

After noticing these failures with 1.1.9, I downgraded to 1.1.8, and eventually back to the last-known-good 1.1.4. The problem continued to occur. Once I downgraded poetry-core from 1.0.5 to 1.0.4, the issue resolved (with both poetry 1.1.4 and 1.1.9).

This looks vaguely familiar to other issues like https://github.com/python-poetry/poetry/issues/3456, and I also encountered something that looks like https://github.com/python-poetry/poetry/issues/4523 today while debugging, but I think those issues are distinct from this specific problem.

[neersighted]

Closing this as there have been no reports recently of anything related, and there was not a reproduction in this issue. If you’re running into something similar, please open a new issue after troubleshooting as much as you can (and consider reaching on Discord if you need help troubleshooting).

[tmehlinger]

We just ran into this on my team.

For us, the problem was one of our teammates had an older version of Poetry installed (1.0.5) and generated a lockfile. When we tried to install dependencies in a Docker image with Poetry 1.1.8, it failed with the stack trace given in the original report above. Regenerating the lock file with 1.1.8 resolved the problem.