Poetry 2.1.0 Regression: Could not parse version constraint: ==*

[medley56]

Description

Today's Poetry release 2.1.0 breaks on poetry install citing Could not parse version constraint: ==* (note that the exact version string cited is probably variable depending on your pyproject.toml file). This version, ==* does not appear in pyproject.toml (see below).

Workarounds

Downgrade to poetry 2.0.1

poetry self update 2.0.1

Poetry Installation Method

install.python-poetry.org

Operating System

MacOS 15.3

Poetry Version

Poetry (version 2.1.0)

Poetry Configuration

❯ poetry config --list
cache-dir = "/Users/game1390/Library/Caches/pypoetry"
data-dir = "/Users/game1390/Library/Application Support/pypoetry"
installer.max-workers = null
installer.no-binary = null
installer.only-binary = null
installer.parallel = true
installer.re-resolve = true
keyring.enabled = true
python.installation-dir = "{data-dir}/python"  # /Users/game1390/Library/Application Support/pypoetry/python
requests.max-retries = 0
solver.lazy-wheel = true
system-git-client = false
virtualenvs.create = true
virtualenvs.in-project = true
virtualenvs.options.always-copy = false
virtualenvs.options.no-pip = false
virtualenvs.options.system-site-packages = false
virtualenvs.path = "{cache-dir}/virtualenvs"  # /Users/game1390/Library/Caches/pypoetry/virtualenvs
virtualenvs.prompt = "{project_name}-py{python_version}"
virtualenvs.use-poetry-python = false

Python Sysconfig

sysconfig.log

Example pyproject.toml

[tool.poetry]
name = "my_package"
version = "5.1.0rc1"
description = "blah"
license = "BSD-3-Clause"
readme = "README.md"
include = ["LICENSE.txt", "CITATION.cff"]


[tool.poetry.dependencies]
python = ">=3.9"
lxml = ">=4.8.0"
click = "^8.0"
rich = "^13.0"
# Extras dependencies
xarray = { version = ">2024.0.0", optional = true }
numpy = { version = "^2.0.0", optional = true }
pre-commit = { version = "*", optional = true }
pytest = { version = "*", optional = true }
pytest-benchmark = { version = "*", optional = true }
pytest-randomly = { version = "*", optional = true }
pytest-cov = { version = "*", optional = true }
pyyaml = { version = "*", optional = true }
ruff = { version = "*", optional = true }
sphinx = { version = "*", optional = true }
myst-parser = { version = "*", optional = true }
sphinx-autoapi = { version = "*", optional = true }
sphinx-rtd-theme = { version = "*", optional = true }

[tool.poetry.group.dev.dependencies]
pre-commit = "*"
pytest = "*"
pytest-benchmark = "*"
pytest-randomly = "*"
pytest-cov = "*"
pyyaml = "*"
ruff = "*"
sphinx = "*"
myst-parser = "*"
sphinx-autoapi = "*"
sphinx-rtd-theme = "*"
coverage = "*"

[tool.poetry.group.examples]
optional = true

[tool.poetry.group.examples.dependencies]
matplotlib = ">=3.4"
memory-profiler = "^0.61.0"

[tool.poetry.extras]
xarray = ["xarray", "numpy"]
test = ["pytest", "pytest-benchmark", "pytest-randomly", "pytest-cov"]
dev = ["xarray", "numpy", "pre-commit", "pytest", "pytest-benchmark", "pytest-randomly",
       "pytest-cov", "ruff", "pyyaml", "sphinx", "myst-parser", "sphinx-autoapi", "sphinx-rtd-theme"]

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"

Poetry Runtime Logs

poetry-runtime.log

Loading configuration file /Users/game1390/Library/Application Support/pypoetry/config.toml
Using virtualenv: /Users/game1390/Workspace/space_packet_parser/.venv
Checking keyring availability: Checking if keyring is available
[keyring:keyring.backend] Loading KWallet
[keyring:keyring.backend] Loading SecretService
[keyring:keyring.backend] Loading Windows
[keyring:keyring.backend] Loading chainer
[keyring:keyring.backend] Loading libsecret
[keyring:keyring.backend] Loading macOS
Using keyring backend 'macOS Keyring'
Available
Installing dependencies from lock file

Finding the necessary packages for the current system

Package operations: 0 installs, 0 updates, 0 removals, 50 skipped

- Installing alabaster (0.7.16): Skipped for the following reason: Already installed
- Installing astroid (3.3.8): Skipped for the following reason: Already installed
- Installing babel (2.17.0): Skipped for the following reason: Already installed
- Installing certifi (2025.1.31): Skipped for the following reason: Already installed
- Installing cfgv (3.4.0): Skipped for the following reason: Already installed
- Installing charset-normalizer (3.4.1): Skipped for the following reason: Already installed
- Installing click (8.1.8): Skipped for the following reason: Already installed
- Installing coverage (7.6.12): Skipped for the following reason: Already installed
- Installing distlib (0.3.9): Skipped for the following reason: Already installed
- Installing docutils (0.21.2): Skipped for the following reason: Already installed
- Installing filelock (3.17.0): Skipped for the following reason: Already installed
- Installing identify (2.6.7): Skipped for the following reason: Already installed
- Installing idna (3.10): Skipped for the following reason: Already installed
- Installing imagesize (1.4.1): Skipped for the following reason: Already installed
- Installing iniconfig (2.0.0): Skipped for the following reason: Already installed
- Installing jinja2 (3.1.5): Skipped for the following reason: Already installed
- Installing lxml (5.3.1): Skipped for the following reason: Already installed
- Installing markdown-it-py (3.0.0): Skipped for the following reason: Already installed
- Installing markupsafe (3.0.2): Skipped for the following reason: Already installed
- Installing mdit-py-plugins (0.4.2): Skipped for the following reason: Already installed
- Installing mdurl (0.1.2): Skipped for the following reason: Already installed
- Installing myst-parser (3.0.1): Skipped for the following reason: Already installed
- Installing nodeenv (1.9.1): Skipped for the following reason: Already installed
- Installing packaging (24.2): Skipped for the following reason: Already installed
- Installing platformdirs (4.3.6): Skipped for the following reason: Already installed
- Installing pluggy (1.5.0): Skipped for the following reason: Already installed
- Installing pre-commit (4.1.0): Skipped for the following reason: Already installed
- Installing py-cpuinfo (9.0.0): Skipped for the following reason: Already installed
- Installing pygments (2.19.1): Skipped for the following reason: Already installed
- Installing pytest (8.3.4): Skipped for the following reason: Already installed
- Installing pytest-benchmark (5.1.0): Skipped for the following reason: Already installed
- Installing pytest-cov (6.0.0): Skipped for the following reason: Already installed
- Installing pytest-randomly (3.16.0): Skipped for the following reason: Already installed
- Installing pyyaml (6.0.2): Skipped for the following reason: Already installed
- Installing requests (2.32.3): Skipped for the following reason: Already installed
- Installing rich (13.9.4): Skipped for the following reason: Already installed
- Installing ruff (0.9.6): Skipped for the following reason: Already installed
- Installing snowballstemmer (2.2.0): Skipped for the following reason: Already installed
- Installing sphinx (7.4.7): Skipped for the following reason: Already installed
- Installing sphinx-autoapi (3.5.0): Skipped for the following reason: Already installed
- Installing sphinx-rtd-theme (3.0.2): Skipped for the following reason: Already installed
- Installing sphinxcontrib-applehelp (2.0.0): Skipped for the following reason: Already installed
- Installing sphinxcontrib-devhelp (2.0.0): Skipped for the following reason: Already installed
- Installing sphinxcontrib-htmlhelp (2.1.0): Skipped for the following reason: Already installed
- Installing sphinxcontrib-jquery (4.1): Skipped for the following reason: Already installed
- Installing sphinxcontrib-jsmath (1.0.1): Skipped for the following reason: Already installed
- Installing sphinxcontrib-qthelp (2.0.0): Skipped for the following reason: Already installed
- Installing sphinxcontrib-serializinghtml (2.0.0): Skipped for the following reason: Already installed
- Installing urllib3 (2.3.0): Skipped for the following reason: Already installed
- Installing virtualenv (20.29.2): Skipped for the following reason: Already installed

Installing the current project: space_packet_parser (5.1.0rc1)
- Building package space-packet-parser in editable mode
- Removed space_packet_parser-5.1.0rc1.dist-info directory from /Users/game1390/Workspace/space_packet_parser/.venv/lib/python3.12/site-packages
- Adding space_packet_parser.pth to /Users/game1390/Workspace/space_packet_parser/.venv/lib/python3.12/site-packages for /Users/game1390/Workspace/space_packet_parser
- Adding the spp script to /Users/game1390/Workspace/space_packet_parser/.venv/bin
- Adding the space_packet_parser-5.1.0rc1.dist-info directory to /Users/game1390/Workspace/space_packet_parser/.venv/lib/python3.12/site-packages

[joein]

I have also encountered this problem and just opened another issue #10185 (I closed it as a duplicate)

I found a workaround for those who encounter it due to python version constraints, however, it does not seem to be the case here. I described it in #10185

[dillonco]

Just encountered the same error with a newly created poetry project on Windows 11.
Using the workaround to downgrade from 2.1.0 to 2.0.1 also fixed it for me.

[grudloff]

Started testing poetry today for the first time, and I was losing my mind over this error

[soumanta-yugen]

Started seeing this issue as well. I have a Github action that installs Poetry and then installs dependencies. The install dependencies fails with the Could not parse version constraint: ==* error.

- name: Install Poetry
  run: |
    curl -sSL https://install.python-poetry.org | python3 -

- name: Configure Poetry
  run: |
    poetry config virtualenvs.create true
    poetry config virtualenvs.in-project true

- name: Install dependencies
  run: |
    poetry install --with dev,test

Sharing the toml file below in case it helps.

pyproject.toml

Expand to see details

[tool.poetry]
name = "risk-ai-agents"
version = "0.1.0"
description = "AI Agents for Risk Decisioning & Fraud Management"
authors = ["Soumanta Das <soumanta@yugen.ai>"]
readme = "README.md"
packages = [
    {include = "agent_backend", from = "src"},
    {include = "tools", from = "src"}
]

[tool.poetry.dependencies]
python = ">=3.10,<3.13"
swarm = { git = "https://github.com/openai/swarm.git" }
fastapi = "0.115.5"
fire = "0.7.0"
numpy = ">=2.0.0"
openai = "1.55.3"
pandas = ">=2.0.0"
pydantic = "2.9.2"
requests = "2.32.3"
typing-extensions = "4.12.2"
uvicorn = "0.32.0"
redis = "5.0.1"
networkx = "3.2.1"
pyarrow = "18.1.0"
scipy = ">=1.12"

[tool.poetry.group.dev.dependencies]
black = "^24.0"
isort = "^5.0"
mypy = "1.13.0"
ruff = "0.7.4"
pipreqs = "0.5.0"
flake8 = "7.0.0"

[tool.poetry.group.test.dependencies]
pytest = "^6.0"
pytest-cov = "^2.0"
pytest-asyncio = "^0.14.0"

[tool.poetry.group.docs.dependencies]
mkdocs = "^1.1.2"
mkdocs-material = "^8.0.0"
mkdocstrings = {extras = ["python"], version = "^0.18.0"}

[build-system]
requires = ["poetry-core"]
build-backend = "poetry.core.masonry.api"

[tool.black]
line-length = 88
target-version = ['py38']
include = '\.pyi?$'

[tool.isort]
profile = "black"
multi_line_output = 3
include_trailing_comma = true
force_grid_wrap = 0
use_parentheses = true
line_length = 88

[tool.ruff]
select = ["E", "F", "B"]
ignore = ["E501"]
line-length = 88
target-version = "py38"