poetry install | SolverProblemError Because my_project depends on string (*) which doesn't match any versions, version solving failed - solver

Question

I am yet to use poetry to run project, so excuse lack of understanding.
I successfully installed the poetry python library manager, using:
curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py | python3
Next step poetry install initially returned this error:
me#LAPTOP-G1DAPU88:~/.ssh/workers-python/workers$ poetry install
RuntimeError
Poetry could not find a pyproject.toml file in /home/me/.ssh/workers-python/workers or its parents
at ~/.poetry/lib/poetry/_vendor/py3.8/poetry/core/factory.py:369 in locate
365│ if poetry_file.exists():
366│ return poetry_file
367│
368│ else:
→ 369│ raise RuntimeError(
370│ "Poetry could not find a pyproject.toml file in {} or its parents".format(
371│ cwd
372│ )
373│ )
I soon realised I needed my own made pyproject.toml file. Running poetry install again yielded:
$ poetry install
TOMLError
Invalid TOML file /home/me/.ssh/workers-python/workers/pyproject.toml: Key "json " already exists.
at ~/.poetry/lib/poetry/_vendor/py3.8/poetry/core/toml/file.py:34 in read
30│ def read(self): # type: () -> "TOMLDocument"
31│ try:
32│ return super(TOMLFile, self).read()
33│ except (ValueError, TOMLKitError) as e:
→ 34│ raise TOMLError("Invalid TOML file {}: {}".format(self.path.as_posix(), e))
35│
36│ def __getattr__(self, item): # type: (str) -> Any
37│ return getattr(self.__path, item)
38│
Above error indicates there were duplicate entries.
Running poetry install again with the now updated pyproject.toml file in cwd threw this error (in the post's title):
$ poetry install
Creating virtualenv my_project-1_EUeV5I-py3.8 in /home/me/.cache/pypoetry/virtualenvs
Updating dependencies
Resolving dependencies... (28.4s)
SolverProblemError
Because my_project depends on string (*) which doesn't match any versions, version solving failed.
at ~/.poetry/lib/poetry/puzzle/solver.py:241 in _solve
237│ packages = result.packages
238│ except OverrideNeeded as e:
239│ return self.solve_in_compatibility_mode(e.overrides, use_latest=use_latest)
240│ except SolveFailure as e:
→ 241│ raise SolverProblemError(e)
242│
243│ results = dict(
244│ depth_first_search(
245│ PackageNode(self._package, packages), aggregate_package_nodes
However, temporarily removing all instances = "*" gave me this error of \n on line 12... which doesn't appear to be there:
$ poetry install
TOMLError
Invalid TOML file /home/me/.ssh/workers-python/workers/pyproject.toml: Unexpected character: '\n' at line 12 col 5
at ~/.poetry/lib/poetry/_vendor/py3.8/poetry/core/toml/file.py:34 in read
30│ def read(self): # type: () -> "TOMLDocument"
31│ try:
32│ return super(TOMLFile, self).read()
33│ except (ValueError, TOMLKitError) as e:
→ 34│ raise TOMLError("Invalid TOML file {}: {}".format(self.path.as_posix(), e))
35│
36│ def __getattr__(self, item): # type: (str) -> Any
37│ return getattr(self.__path, item)
38│
me#LAPTOP-G1DAPU88:~/.ssh/workers-python/workers$ cat pyproject.toml
[tool.poetry]
name = "my_project"
version = "0.1.0"
description = "Top-level package for my_project."
authors = [""]
packages = [
{ include = "my_project"},
]
[tool.poetry.dependencies]
python = "^3.8"
click # Suspect line
I have reverted this.
Current pyproject.toml:
[tool.poetry]
name = "data_simulator"
version = "0.1.0"
description = "Top-level package for data_simulator."
authors = ["iotahoe <iotahoe#iotahoe.com>"] # daniel.bell#hitachivantara.com / daniel#iotahoe.com
packages = [
{ include = "data_simulator"},
]
[tool.poetry.dependencies]
python = "^3.8"
click = "*"
#logging = "*"
#os = "*"
#pathlib = "*"
#time = "*"
numpy = "*"
pandas = "*"
#json = "*"
#random = "*"
faker = "*"
transformers = "4.4.2"
#re = "*"
#itertools = "*"
#datetime = "*"
#requests = "*"
#copy = "*"
#collections = "*"
#collections.abc = "*"
#multiprocessing = "*"
#multiprocessing.dummy = "*"
nltk = "*"
#nltk.corpus = "*"
#string = "*"
[tool.poetry.dev-dependencies]
isort = "5.6.4"
black = "^20.8b1"
invoke = "^1.4.1"
coveralls = "^2.2.0"
pytest = "^3.0"
flake8 = "^3.8.3"
mypy = "^0.782"
[[tool.poetry.source]]
name = "azure"
url = "https://pkgs.dev.azure.com/iotahoe/Halo/_packaging/private-sources/pypi/simple/"
secondary = true
[build-system]
requires = ["poetry>=0.12"]
build-backend = "poetry.masonry.api"
Note: 'name', 'authors', 'include', 'url' have been censored.

Answer 1

As a general advise I recommend to use poetry's command line instead of creating/manipulating the pyproject.toml.
Start with a poetry init or poetry init -n and add your dependencies with poetry add.
The problem with your current pyproject.toml is, that you declare built-in packages as dependencies, like os, pathlib, string and others. This is why you receive the message Because my_project depends on string (*) which doesn't match any versions, version solving failed., which means poetry cannot find any matching package information in the repository.

Answer 2

tl;dr: Flush the *.egg-info directories before running poetry lock.
This answer is not strictly related to the current issue, but a similar error message can appear in other circumstances, so I think it's valuable to share it here.
If you are locking in a project where sub-dependencies are directly available on the file system, some *.egg-info directories may interfere with the locking process, causing issues when trying to run poetry install in a context where those *.egg-info files are missing. To avoid the problem: Flush the *.egg-info directories prior to locking. You should then have an updated poetry.lock file with more content.