Write documentation for ResolutionImpossible error message #8459

nlhkabu · 2020-06-17T19:56:26Z

Related to #8377

We need to write documentation to help users when they experience a ResolutionImpossible error message.

Archived drafts:

Version 1

Fixing conflicting dependencies

Note: the purpose of this documentation is to provide practical suggestions to pip users who encounter an error where pip cannot install their specified packages due to conflicting dependencies (a ResolutionImpossible error).
This documentation is not meant to act as a list of PyPA agreed best practices or recommendations, but rather an attempt to help users who find themselves stuck and are unsure what steps they can take to solve their problem.

Understanding your error message

When you get a ResolutionImpossible error, you might see something like this:

pip install ward==0.44.1b0 py2neo==4.3.0
Due to conflicting dependencies pip cannot install ward and py2neo:
- ward depends on pygments<3.0.0,>=2.4.2
- py2neo depends on pygments~=2.3.1

In this example, pip cannot install the packages you have requested, because they each depend on different versions of the same package (pygments):

ward version 0.44.1b0 depends on a version of pygments that is less than 3.0.0 but greater than or equal to 2.4.2
py2neo version 4.3.0 depends on a pygments release that is compatible with version 2.3.1

Sometimes these messages are straightforward to read, because they use commonly understood comparison operators to specify the required version (e.g. < or >).

However, Python packaging also supports some more complex ways for specifying package versions. Here is the full list supported comparison operators:

Operator	Description	Example
`>`	Any version greater than the specified version	`>3.1`: any version greater than `3.1`
`<`	Any version less than the specified version	`<3.1`: any version less than `3.1`
`<=`	Any version less than or equal to the specified version	`<=3.1`: any version less than or equal to `3.1`
`>=`	Any version greater than or equal to the specified version	`>=3.1`: version `3.1` and greater
`==`	Exactly the specified version	`==3.1`: only version `3.1`
`!=`	Any version not equal to the specified version	`!=3.1`: any version other than `3.1`
`~=`	Any compatible release. Compatible releases are releases that are within the same major or minor version, assuming the package author is using semantic versioning.	`~=3.1`: version `3.1` or later, but not version `4.0` or later. `~=3.1.2`: version `3.1.2` or later, but not version `3.2.0` or later.
`*`	Can be used at the end of a version number to represent "all"	*`== 3.1.`:** any version that starts with `3.1`. Equivalent to `~=3.1.0`.

The full specification of supported comparison operators can be found in PEP440.

Error causes

There are three common causes for experiencing a ResolutionImpossible error.
The cause and possible solution to your error will depend on your individual use case.

1. Your "top level" requirements are too strict

In this scenario, the packages that you have asked pip to install are incompatible, possibly because you have been strict when you specified the package version.

In the example above both ward and py2neo have been pinned to use specific versions (ward==0.44.1b0 py2neo==4.3.0).

To find a version of both ward and py2neo that depend on the same version of pygments, you might consider:

Loosening the range of packages that you are prepared to install (e.g. pip install "ward>0.44.*" "py2neo>4.0.0")
Asking pip to install any version of ward and py2neo by removing the version specifiers altogether (e.g. pip install ward py2neo)

In the second case, pip will automatically find a version of both ward and py2neo that depend on the same version of pygments, installing:

ward 0.46.0b0, which depends on pygments 2.6.1
py2neo 4.3.0 which also depends on pygments 2.6.1

If you want to prioritise one package over another, you can add version specifiers to only the more important package:

pip install ward==0.44.1b0 py2neo

This will result in:

ward 0.44.1b0, which depends on pygments 2.6.1
py2neo 4.1.3 which also depends on pygments 2.6.1

Now that you have resolved the issue, you can repin the compatible package versions as required.

2. A package that you are using has requirements that are too strict

You may find yourself in a situation where a package you are trying to install has specific dependency requirements that create a conflict. This is known as a downstream dependency conflict.

Assuming that you cannot resolve the conflict by loosening the version of the package you require (as above), you can try to fix the issue on the package itself by:

Requesting that the package maintainers loosen their dependencies
Forking the package and loosening the dependencies yourself

As a general rule, third party modules (libraries) should strive to reduce the the likelihood of causing dependency conflicts with other libraries by keeping their dependency requirements as loose as possible.

3. All requirements are loose, but a solution does not exist

Sometimes it's simply impossible to find a combination of package versions that do not conflict. Welcome to dependency hell.

In this situation, you can consider:

Using an alternative package, if that is acceptable for your project (see Awesome Python for similar packages)
Forking and refactoring one of your dependencies to avoid the conflict

Overriding dependency resolution (force installing)

There is currently no way to override pip's mechanism for resolving dependency conflicts and forcing pip to install an incompatible version of a required package.

If you would like to see this functionality please let the pip team know.

Version 2

Fixing conflicting dependencies

Note: the purpose of this documentation is to provide practical suggestions to pip users who encounter an error where pip cannot install their specified packages due to conflicting dependencies (a ResolutionImpossible error).
This documentation is not meant to act as a list of PyPA agreed best practices or recommendations, but rather an attempt to help users who find themselves stuck and are unsure what steps they can take to solve their problem.

Understanding your error message

When you get a ResolutionImpossible error, you might see something like this:

pip install packageA==0.44.1b0 packageB==4.3.0
Due to conflicting dependencies pip cannot install packageA and packageB:
- packageA depends on packageC<3.0.0,>=2.4.2
- packageB depends on packageC~=2.3.1

In this example, pip cannot install the packages you have requested, because they each depend on different versions of the same package (packageC):

packageA version 0.44.1b0 depends on a version of packageC that is less than 3.0.0 but greater than or equal to 2.4.2
packageB version 4.3.0 depends on a packageC release that is compatible with version 2.3.1

Sometimes these messages are straightforward to read, because they use commonly understood comparison operators to specify the required version (e.g. < or >).

However, Python packaging also supports some more complex ways for specifying package versions. Here is the full list supported comparison operators:

Operator	Description	Example
`>`	Any version greater than the specified version	`>3.1`: any version greater than `3.1`
`<`	Any version less than the specified version	`<3.1`: any version less than `3.1`
`<=`	Any version less than or equal to the specified version	`<=3.1`: any version less than or equal to `3.1`
`>=`	Any version greater than or equal to the specified version	`>=3.1`: version `3.1` and greater
`==`	Exactly the specified version	`==3.1`: only version `3.1`
`!=`	Any version not equal to the specified version	`!=3.1`: any version other than `3.1`
`~=`	Any compatible release. Compatible releases are releases that are within the same major or minor version, assuming the package author is using semantic versioning.	`~=3.1`: version `3.1` or later, but not version `4.0` or later. `~=3.1.2`: version `3.1.2` or later, but not version `3.2.0` or later.
`*`	Can be used at the end of a version number to represent "all"	*`== 3.1.`:** any version that starts with `3.1`. Equivalent to `~=3.1.0`.

The full specification of supported comparison operators can be found in PEP440.

Error causes

There are three common causes for experiencing a ResolutionImpossible error.
The cause and possible solution to your error will depend on your individual use case.

1. Your "top level" requirements are too strict

In this scenario, the packages that you have asked pip to install are incompatible, possibly because you have been strict when you specified the package version.

In the example above both packageA and packageB have been pinned to use specific versions (packageA==0.44.1b0 packageB==4.3.0).

To find a version of both packageA and packageB that depend on the same version of packageC, you might consider:

Loosening the range of packages that you are prepared to install (e.g. pip install "packageA>0.44.*" "packageB>4.0.0")
Asking pip to install any version of packageA and packageB by removing the version specifiers altogether (e.g. pip install packageA packageB)

In the second case, pip will automatically find a version of both packageA and packageB that depend on the same version of packageC, installing:

packageA 0.46.0b0, which depends on packageC 2.6.1
packageB 4.3.0 which also depends on packageC 2.6.1

If you want to prioritise one package over another, you can add version specifiers to only the more important package:

pip install packageA==0.44.1b0 packageB

This will result in:

packageA 0.44.1b0, which depends on packageC 2.6.1
packageB 4.1.3 which also depends on packageC 2.6.1

Now that you have resolved the issue, you can repin the compatible package versions as required.

2. A package that you are using has requirements that are too strict

You may find yourself in a situation where a package you are trying to install has specific dependency requirements that create a conflict. This is known as a downstream dependency conflict.

Assuming that you cannot resolve the conflict by loosening the version of the package you require (as above), you can try to fix the issue on the package itself by:

Requesting that the package maintainers loosen their dependencies
Forking the package and loosening the dependencies yourself

As a general rule, third party modules (libraries) should strive to reduce the the likelihood of causing dependency conflicts with other libraries by keeping their dependency requirements as loose as possible.

3. All requirements are loose, but a solution does not exist

Sometimes it's simply impossible to find a combination of package versions that do not conflict. Welcome to dependency hell.

In this situation, you can consider:

Using an alternative package, if that is acceptable for your project (see Awesome Python for similar packages)
Forking and refactoring one of your dependencies to avoid the conflict

Overriding dependency resolution (force installing)

There is currently no way to override pip's mechanism for resolving dependency conflicts and forcing pip to install an incompatible version of a required package.

If you would like to see this functionality please let the pip team know.

Version 3

Fixing conflicting dependencies

The purpose of this documentation is to provide practical suggestions to pip users who encounter an error where pip cannot install their specified packages due to conflicting dependencies (a ResolutionImpossible error).

Understanding your error message

When you get a ResolutionImpossible error, you might see something like this:

pip install packageA==0.44.1b0 packageB==4.3.0
Due to conflicting dependencies pip cannot install packageA and packageB:
- packageA depends on packageC<3.0.0,>=2.4.2
- packageB depends on packageC~=2.3.1

In this example, pip cannot install the packages you have requested, because they each depend on different versions of the same package (packageC):

packageA version 0.44.1b0 depends on a version of packageC that is less than 3.0.0 but greater than or equal to 2.4.2
packageB version 4.3.0 depends on a packageC release that is compatible with version 2.3.1

Sometimes these messages are straightforward to read, because they use commonly understood comparison operators to specify the required version (e.g. < or >).

However, Python packaging also supports some more complex ways for specifying package versions. Here is the full list supported comparison operators:

Operator	Description	Example
`>`	Any version greater than the specified version	`>3.1`: any version greater than `3.1`
`<`	Any version less than the specified version	`<3.1`: any version less than `3.1`
`<=`	Any version less than or equal to the specified version	`<=3.1`: any version less than or equal to `3.1`
`>=`	Any version greater than or equal to the specified version	`>=3.1`: version `3.1` and greater
`==`	Exactly the specified version	`==3.1`: only version `3.1`
`!=`	Any version not equal to the specified version	`!=3.1`: any version other than `3.1`
`~=`	Any compatible release. Compatible releases are releases that are within the same major or minor version, assuming the package author is using semantic versioning.	`~=3.1`: version `3.1` or later, but not version `4.0` or later. `~=3.1.2`: version `3.1.2` or later, but not version `3.2.0` or later.
`*`	Can be used at the end of a version number to represent "all"	*`== 3.1.`:** any version that starts with `3.1`. Equivalent to `~=3.1.0`.

The full specification of supported comparison operators can be found in PEP440.

Error causes

There are three common causes for experiencing a ResolutionImpossible error.
The cause and possible solution to your error will depend on your individual use case.

1. Your "top level" requirements are too strict

In this scenario, the packages that you have asked pip to install are incompatible, possibly because you have been strict when you specified the package version.

In the example above both packageA and packageB have been pinned to use specific versions (packageA==0.44.1b0 packageB==4.3.0).

To find a version of both packageA and packageB that depend on the same version of packageC, you might consider:

Loosening the range of packages that you are prepared to install (e.g. pip install "packageA>0.44.*" "packageB>4.0.0")
Asking pip to install any version of packageA and packageB by removing the version specifiers altogether (e.g. pip install packageA packageB)

In the second case, pip will automatically find a version of both packageA and packageB that depend on the same version of packageC, installing:

packageA 0.46.0b0, which depends on packageC 2.6.1
packageB 4.3.0 which also depends on packageC 2.6.1

If you want to prioritise one package over another, you can add version specifiers to only the more important package:

pip install packageA==0.44.1b0 packageB

This will result in:

packageA 0.44.1b0, which depends on packageC 2.6.1
packageB 4.1.3 which also depends on packageC 2.6.1

Now that you have resolved the issue, you can repin the compatible package versions as required.

2. A package that you are using has requirements that are too strict

You may find yourself in a situation where a package you are trying to install has specific dependency requirements that create a conflict. This is known as a downstream dependency conflict.

Assuming that you cannot resolve the conflict by loosening the version of the package you require (as above), you can try to fix the issue on the package itself by:

Requesting that the package maintainers loosen their dependencies
Forking the package and loosening the dependencies yourself

As a general rule, third party modules (libraries) should strive to reduce the the likelihood of causing dependency conflicts with other libraries by keeping their dependency requirements as loose as possible.

3. All requirements are loose, but a solution does not exist

Sometimes it's simply impossible to find a combination of package versions that do not conflict. Welcome to dependency hell.

In this situation, you can consider using an alternative package, if that is acceptable for your project. Seee Awesome Python for similar packages.

Getting help

If none of the suggestions above work for you, we recommend that you ask for help on:

See "How do I ask a good question?" for tips on asking for help.

Unfortunately, the pip team cannot provide support for individual conflict errors. Please only open a ticket on the pip issue tracker if you believe that your problem has exposed a bug in pip.

Version 4

Fixing conflicting dependencies (v. 17 June)

The purpose of this documentation is to provide practical suggestions to pip users who encounter an error where pip cannot install their specified packages due to conflicting dependencies (a ResolutionImpossible error).

Understanding your error message

When you get a ResolutionImpossible error, you might see something like this:

pip install packageA==0.44.1 packageB==4.3.0
Due to conflicting dependencies pip cannot install packageA and packageB:
- packageA depends on packageC<3.0.0,>=2.4.2
- packageB depends on packageC==2.3.1

In this example, pip cannot install the packages you have requested, because they each depend on different versions of the same package (packageC):

packageA version 0.44.1 depends on a version of packageC that is less than 3.0.0 but greater than or equal to 2.4.2
packageB version 4.3.0 depends on version 2.3.1 of packageC

Sometimes these messages are straightforward to read, because they use commonly understood comparison operators to specify the required version (e.g. < or >).

However, Python packaging also supports some more complex ways for specifying package versions (e.g. ~= or *).

View the full list supported comparison operators

Operator	Description	Example
`>`	Any version greater than the specified version	`>3.1`: any version greater than `3.1`
`<`	Any version less than the specified version	`<3.1`: any version less than `3.1`
`<=`	Any version less than or equal to the specified version	`<=3.1`: any version less than or equal to `3.1`
`>=`	Any version greater than or equal to the specified version	`>=3.1`: version `3.1` and greater
`==`	Exactly the specified version	`==3.1`: only version `3.1`
`!=`	Any version not equal to the specified version	`!=3.1`: any version other than `3.1`
`~=`	Any compatible release. Compatible releases are releases that are within the same major or minor version, assuming the package author is using semantic versioning.	`~=3.1`: version `3.1` or later, but not version `4.0` or later. `~=3.1.2`: version `3.1.2` or later, but not version `3.2.0` or later.
`*`	Can be used at the end of a version number to represent "all"	*`== 3.1.`:** any version that starts with `3.1`. Equivalent to `~=3.1.0`.

The detailed specification of supported comparison operators can be found in PEP440.

Determining the origin of your conflict

In order to resolve your conflict, it's useful to understand that conflicts can occur between your "top level requirements" - packages you told pip to install - and "downstream dependencies" - packages required by your top level requirements.

1. Conflicts in your downstream dependencies

As in our example above, you may experience conflicts between your downstream dependencies (also known as "transitive dependencies"). This can happen at a high level:

Or deeper within your dependency tree:

2. Conflicts between your top level requirements and your downstream dependencies

Sometimes, a top level requirement is also a downstream dependency of one of your other packages:

To trace the origin of your conflict, you can run pip in verbose mode

Possible solutions

The solution to your error will depend on your individual use case. Here are some things to try:

1. Audit your top level requirements

As a first step it is useful to audit your project and remove any unneccessary or out of date requirements. Removing these can significantly reduce the complexity of your dependency tree, thereby reducing opportunities for conflicts to occur.

2. Loosen your top level requirements

Sometimes the packages that you have asked pip to install are incompatible because you have been too strict when you specified the package version.

In our first example both packageA and packageB have been pinned to use specific versions (packageA==0.44.1b0 packageB==4.3.0).

To find a version of both packageA and packageB that depend on the same version of packageC, you might consider:

Loosening the range of packages that you are prepared to install (e.g. pip install "packageA>0.44.*" "packageB>4.0.0")
Asking pip to install any version of packageA and packageB by removing the version specifiers altogether (e.g. pip install packageA packageB)

In the second case, pip will automatically find a version of both packageA and packageB that depend on the same version of packageC, installing:

packageA 0.46.0b0, which depends on packageC 2.6.1
packageB 4.3.0 which also depends on packageC 2.6.1

If you want to prioritise one package over another, you can add version specifiers to only the more important package:

pip install packageA==0.44.1b0 packageB

This will result in:

packageA 0.44.1b0, which depends on packageC 2.6.1
packageB 4.1.3 which also depends on packageC 2.6.1

Now that you have resolved the issue, you can repin the compatible package versions as required.

3. Loosen the requirements of your downstream dependencies

Assuming that you cannot resolve the conflict by loosening the version of the package you require (as above), you can try to fix the issue on your downstream dependency by:

Requesting that the package maintainers loosen their dependencies
Forking the package and loosening the dependencies yourself

Warning: If you choose to fork the package yourself, you are opting out of any support provided by the package maintainers. Proceed at your own risk!

4. All requirements are loose, but a solution does not exist

Sometimes it's simply impossible to find a combination of package versions that do not conflict. Welcome to dependency hell.

In this situation, you could consider:

Using an alternative package, if that is acceptable for your project. See Awesome Python for similar packages.
Refactoring your project to reduce the number of dependencies (for example, by breaking up a monolithic code base into smaller pieces)

Getting help

If none of the suggestions above work for you, we recommend that you ask for help on:

See "How do I ask a good question?" for tips on asking for help.

Unfortunately, the pip team cannot provide support for individual dependency conflict errors. Please only open a ticket on the pip issue tracker if you believe that your problem has exposed a bug in pip.

The text was updated successfully, but these errors were encountered:

nlhkabu · 2020-06-17T20:57:38Z

@pfmoore @uranusjr @pradyunsg @ei8fdb
https://hackmd.io/bJ69K88tSa-6wRy4mo6D9A is ready for review - please read and add comments.

195: Update pip to 20.3 r=duckinator a=pyup-bot This PR updates [pip](https://pypi.org/project/pip) from **20.2.4** to **20.3**. <details> <summary>Changelog</summary> ### 20.3 ``` - Introduce a new ResolutionImpossible error, raised when pip encounters un-satisfiable dependency conflicts (`8546 <https://github.com/pypa/pip/issues/8546>`_, `8377 <https://github.com/pypa/pip/issues/8377>`_) - Add a subcommand ``debug`` to ``pip config`` to list available configuration sources and the key-value pairs defined in them. (`6741 <https://github.com/pypa/pip/issues/6741>`_) - Warn if index pages have unexpected content-type (`6754 <https://github.com/pypa/pip/issues/6754>`_) - Allow specifying ``--prefer-binary`` option in a requirements file (`7693 <https://github.com/pypa/pip/issues/7693>`_) - Generate PEP 376 REQUESTED metadata for user supplied requirements installed by pip. (`7811 <https://github.com/pypa/pip/issues/7811>`_) - Warn if package url is a vcs or an archive url with invalid scheme (`8128 <https://github.com/pypa/pip/issues/8128>`_) - Parallelize network operations in ``pip list``. (`8504 <https://github.com/pypa/pip/issues/8504>`_) - Allow the new resolver to obtain dependency information through wheels lazily downloaded using HTTP range requests. To enable this feature, invoke ``pip`` with ``--use-feature=fast-deps``. (`8588 <https://github.com/pypa/pip/issues/8588>`_) - Support ``--use-feature`` in requirements files (`8601 <https://github.com/pypa/pip/issues/8601>`_) Bug Fixes --------- - Use canonical package names while looking up already installed packages. (`5021 <https://github.com/pypa/pip/issues/5021>`_) - Fix normalizing path on Windows when installing package on another logical disk. (`7625 <https://github.com/pypa/pip/issues/7625>`_) - The VCS commands run by pip as subprocesses don't merge stdout and stderr anymore, improving the output parsing by subsequent commands. (`7968 <https://github.com/pypa/pip/issues/7968>`_) - Correctly treat non-ASCII entry point declarations in wheels so they can be installed on Windows. (`8342 <https://github.com/pypa/pip/issues/8342>`_) - Update author email in config and tests to reflect decommissioning of pypa-dev list. (`8454 <https://github.com/pypa/pip/issues/8454>`_) - Headers provided by wheels in .data directories are now correctly installed into the user-provided locations, such as ``--prefix``, instead of the virtual environment pip is running in. (`8521 <https://github.com/pypa/pip/issues/8521>`_) Vendored Libraries ------------------ - Vendored htmlib5 no longer imports deprecated xml.etree.cElementTree on Python 3. - Upgrade appdirs to 1.4.4 - Upgrade certifi to 2020.6.20 - Upgrade distlib to 0.3.1 - Upgrade html5lib to 1.1 - Upgrade idna to 2.10 - Upgrade packaging to 20.4 - Upgrade requests to 2.24.0 - Upgrade six to 1.15.0 - Upgrade toml to 0.10.1 - Upgrade urllib3 to 1.25.9 Improved Documentation ---------------------- - Add ``--no-input`` option to pip docs (`7688 <https://github.com/pypa/pip/issues/7688>`_) - List of options supported in requirements file are extracted from source of truth, instead of being maintained manually. (`7908 <https://github.com/pypa/pip/issues/7908>`_) - Fix pip config docstring so that the subcommands render correctly in the docs (`8072 <https://github.com/pypa/pip/issues/8072>`_) - replace links to the old pypa-dev mailing list with https://mail.python.org/mailman3/lists/distutils-sig.python.org/ (`8353 <https://github.com/pypa/pip/issues/8353>`_) - Fix example for defining multiple values for options which support them (`8373 <https://github.com/pypa/pip/issues/8373>`_) - Add documentation for the ResolutionImpossible error that helps the user fix dependency conflicts (`8459 <https://github.com/pypa/pip/issues/8459>`_) - Add feature flags to docs (`8512 <https://github.com/pypa/pip/issues/8512>`_) - Document how to install package extras from git branch and source distributions. (`8576 <https://github.com/pypa/pip/issues/8576>`_) ``` ### 20.3b1 ``` =================== Deprecations and Removals ------------------------- - ``pip freeze`` will stop filtering the ``pip``, ``setuptools``, ``distribute`` and ``wheel`` packages from ``pip freeze`` output in a future version. To keep the previous behavior, users should use the new ``--exclude`` option. (`4256 <https://github.com/pypa/pip/issues/4256>`_) - Deprecate support for Python 3.5 (`8181 <https://github.com/pypa/pip/issues/8181>`_) - Document that certain removals can be fast tracked. (`8417 <https://github.com/pypa/pip/issues/8417>`_) - Document that Python versions are generally supported until PyPI usage falls below 5%. (`8927 <https://github.com/pypa/pip/issues/8927>`_) - Deprecate ``--find-links`` option in ``pip freeze`` (`9069 <https://github.com/pypa/pip/issues/9069>`_) Features -------- - Add ``--exclude`` option to ``pip freeze`` and ``pip list`` commands to explicitly exclude packages from the output. (`4256 <https://github.com/pypa/pip/issues/4256>`_) - Allow multiple values for --abi and --platform. (`6121 <https://github.com/pypa/pip/issues/6121>`_) - Add option ``--format`` to subcommand ``list`` of ``pip cache``, with ``abspath`` choice to output the full path of a wheel file. (`8355 <https://github.com/pypa/pip/issues/8355>`_) - Improve error message friendliness when an environment has packages with corrupted metadata. (`8676 <https://github.com/pypa/pip/issues/8676>`_) - Make the ``setup.py install`` deprecation warning less noisy. We warn only when ``setup.py install`` succeeded and ``setup.py bdist_wheel`` failed, as situations where both fails are most probably irrelevant to this deprecation. (`8752 <https://github.com/pypa/pip/issues/8752>`_) - Check the download directory for existing wheels to possibly avoid fetching metadata when the ``fast-deps`` feature is used with ``pip wheel`` and ``pip download``. (`8804 <https://github.com/pypa/pip/issues/8804>`_) - When installing a git URL that refers to a commit that is not available locally after git clone, attempt to fetch it from the remote. (`8815 <https://github.com/pypa/pip/issues/8815>`_) - Include http subdirectory in ``pip cache info`` and ``pip cache purge`` commands. (`8892 <https://github.com/pypa/pip/issues/8892>`_) - Cache package listings on index packages so they are guarenteed to stay stable during a pip command session. This also improves performance when a index page is accessed multiple times during the command session. (`8905 <https://github.com/pypa/pip/issues/8905>`_) - New resolver: Tweak resolution logic to improve user experience when user-supplied requirements conflict. (`8924 <https://github.com/pypa/pip/issues/8924>`_) - Support Python 3.9. (`8971 <https://github.com/pypa/pip/issues/8971>`_) - Log an informational message when backtracking takes multiple rounds on a specific package. (`8975 <https://github.com/pypa/pip/issues/8975>`_) - Switch to the new dependency resolver by default. (`9019 <https://github.com/pypa/pip/issues/9019>`_) - Remove the ``--build-dir`` option, as per the deprecation. (`9049 <https://github.com/pypa/pip/issues/9049>`_) Bug Fixes --------- - Propagate ``--extra-index-url`` from requirements file properly to session auth, so that keyring auth will work as expected. (`8103 <https://github.com/pypa/pip/issues/8103>`_) - Allow specifying verbosity and quiet level via configuration files and environment variables. Previously these options were treated as boolean values when read from there while through CLI the level can be specified. (`8578 <https://github.com/pypa/pip/issues/8578>`_) - Only converts Windows path to unicode on Python 2 to avoid regressions when a POSIX environment does not configure the file system encoding correctly. (`8658 <https://github.com/pypa/pip/issues/8658>`_) - List downloaded distributions before exiting ``pip download`` when using the new resolver to make the behavior the same as that on the legacy resolver. (`8696 <https://github.com/pypa/pip/issues/8696>`_) - New resolver: Pick up hash declarations in constraints files and use them to filter available distributions. (`8792 <https://github.com/pypa/pip/issues/8792>`_) - Avoid polluting the destination directory by resolution artifacts when the new resolver is used for ``pip download`` or ``pip wheel``. (`8827 <https://github.com/pypa/pip/issues/8827>`_) - New resolver: If a package appears multiple times in user specification with different ``--hash`` options, only hashes that present in all specifications should be allowed. (`8839 <https://github.com/pypa/pip/issues/8839>`_) - Tweak the output during dependency resolution in the new resolver. (`8861 <https://github.com/pypa/pip/issues/8861>`_) - Correctly search for installed distributions in new resolver logic in order to not miss packages (virtualenv packages from system-wide-packages for example) (`8963 <https://github.com/pypa/pip/issues/8963>`_) - Do not fail in pip freeze when encountering a ``direct_url.json`` metadata file with editable=True. Render it as a non-editable ``file://`` URL until modern editable installs are standardized and supported. (`8996 <https://github.com/pypa/pip/issues/8996>`_) Vendored Libraries ------------------ - Fix devendoring instructions to explicitly state that ``vendor.txt`` should not be removed. It is mandatory for ``pip debug`` command. Improved Documentation ---------------------- - Add documentation for '.netrc' support. (`7231 <https://github.com/pypa/pip/issues/7231>`_) - Add OS tabs for OS-specific commands. (`7311 <https://github.com/pypa/pip/issues/7311>`_) - Add note and example on keyring support for index basic-auth (`8636 <https://github.com/pypa/pip/issues/8636>`_) - Added initial UX feedback widgets to docs. (`8783 <https://github.com/pypa/pip/issues/8783>`_, `8848 <https://github.com/pypa/pip/issues/8848>`_) - Add ux documentation (`8807 <https://github.com/pypa/pip/issues/8807>`_) - Update user docs to reflect new resolver as default in 20.3. (`9044 <https://github.com/pypa/pip/issues/9044>`_) - Improve migration guide to reflect changes in new resolver behavior. (`9056 <https://github.com/pypa/pip/issues/9056>`_) ``` </details> <details> <summary>Links</summary> - PyPI: https://pypi.org/project/pip - Changelog: https://pyup.io/changelogs/pip/ - Homepage: https://pip.pypa.io/ </details> Co-authored-by: pyup-bot <[email protected]>

194: Update pytest-pylint to 0.18.0 r=duckinator a=pyup-bot This PR updates [pytest-pylint](https://pypi.org/project/pytest-pylint) from **0.17.0** to **0.18.0**. *The bot wasn't able to find a changelog for this release. [Got an idea?](https://github.com/pyupio/changelogs/issues/new)* <details> <summary>Links</summary> - PyPI: https://pypi.org/project/pytest-pylint - Changelog: https://pyup.io/changelogs/pytest-pylint/ - Repo: https://github.com/carsongee/pytest-pylint </details> 197: Update pip to 20.3.1 r=duckinator a=pyup-bot This PR updates [pip](https://pypi.org/project/pip) from **20.2.4** to **20.3.1**. <details> <summary>Changelog</summary> ### 20.3.1 ``` =================== Deprecations and Removals ------------------------- - The --build-dir option has been restored as a no-op, to soften the transition for tools that still used it. (`9193 <https://github.com/pypa/pip/issues/9193>`_) ``` ### 20.3 ``` - Introduce a new ResolutionImpossible error, raised when pip encounters un-satisfiable dependency conflicts (`8546 <https://github.com/pypa/pip/issues/8546>`_, `8377 <https://github.com/pypa/pip/issues/8377>`_) - Add a subcommand ``debug`` to ``pip config`` to list available configuration sources and the key-value pairs defined in them. (`6741 <https://github.com/pypa/pip/issues/6741>`_) - Warn if index pages have unexpected content-type (`6754 <https://github.com/pypa/pip/issues/6754>`_) - Allow specifying ``--prefer-binary`` option in a requirements file (`7693 <https://github.com/pypa/pip/issues/7693>`_) - Generate PEP 376 REQUESTED metadata for user supplied requirements installed by pip. (`7811 <https://github.com/pypa/pip/issues/7811>`_) - Warn if package url is a vcs or an archive url with invalid scheme (`8128 <https://github.com/pypa/pip/issues/8128>`_) - Parallelize network operations in ``pip list``. (`8504 <https://github.com/pypa/pip/issues/8504>`_) - Allow the new resolver to obtain dependency information through wheels lazily downloaded using HTTP range requests. To enable this feature, invoke ``pip`` with ``--use-feature=fast-deps``. (`8588 <https://github.com/pypa/pip/issues/8588>`_) - Support ``--use-feature`` in requirements files (`8601 <https://github.com/pypa/pip/issues/8601>`_) Bug Fixes --------- - Use canonical package names while looking up already installed packages. (`5021 <https://github.com/pypa/pip/issues/5021>`_) - Fix normalizing path on Windows when installing package on another logical disk. (`7625 <https://github.com/pypa/pip/issues/7625>`_) - The VCS commands run by pip as subprocesses don't merge stdout and stderr anymore, improving the output parsing by subsequent commands. (`7968 <https://github.com/pypa/pip/issues/7968>`_) - Correctly treat non-ASCII entry point declarations in wheels so they can be installed on Windows. (`8342 <https://github.com/pypa/pip/issues/8342>`_) - Update author email in config and tests to reflect decommissioning of pypa-dev list. (`8454 <https://github.com/pypa/pip/issues/8454>`_) - Headers provided by wheels in .data directories are now correctly installed into the user-provided locations, such as ``--prefix``, instead of the virtual environment pip is running in. (`8521 <https://github.com/pypa/pip/issues/8521>`_) Vendored Libraries ------------------ - Vendored htmlib5 no longer imports deprecated xml.etree.cElementTree on Python 3. - Upgrade appdirs to 1.4.4 - Upgrade certifi to 2020.6.20 - Upgrade distlib to 0.3.1 - Upgrade html5lib to 1.1 - Upgrade idna to 2.10 - Upgrade packaging to 20.4 - Upgrade requests to 2.24.0 - Upgrade six to 1.15.0 - Upgrade toml to 0.10.1 - Upgrade urllib3 to 1.25.9 Improved Documentation ---------------------- - Add ``--no-input`` option to pip docs (`7688 <https://github.com/pypa/pip/issues/7688>`_) - List of options supported in requirements file are extracted from source of truth, instead of being maintained manually. (`7908 <https://github.com/pypa/pip/issues/7908>`_) - Fix pip config docstring so that the subcommands render correctly in the docs (`8072 <https://github.com/pypa/pip/issues/8072>`_) - replace links to the old pypa-dev mailing list with https://mail.python.org/mailman3/lists/distutils-sig.python.org/ (`8353 <https://github.com/pypa/pip/issues/8353>`_) - Fix example for defining multiple values for options which support them (`8373 <https://github.com/pypa/pip/issues/8373>`_) - Add documentation for the ResolutionImpossible error that helps the user fix dependency conflicts (`8459 <https://github.com/pypa/pip/issues/8459>`_) - Add feature flags to docs (`8512 <https://github.com/pypa/pip/issues/8512>`_) - Document how to install package extras from git branch and source distributions. (`8576 <https://github.com/pypa/pip/issues/8576>`_) ``` ### 20.3b1 ``` =================== Deprecations and Removals ------------------------- - ``pip freeze`` will stop filtering the ``pip``, ``setuptools``, ``distribute`` and ``wheel`` packages from ``pip freeze`` output in a future version. To keep the previous behavior, users should use the new ``--exclude`` option. (`4256 <https://github.com/pypa/pip/issues/4256>`_) - Deprecate support for Python 3.5 (`8181 <https://github.com/pypa/pip/issues/8181>`_) - Document that certain removals can be fast tracked. (`8417 <https://github.com/pypa/pip/issues/8417>`_) - Document that Python versions are generally supported until PyPI usage falls below 5%. (`8927 <https://github.com/pypa/pip/issues/8927>`_) - Deprecate ``--find-links`` option in ``pip freeze`` (`9069 <https://github.com/pypa/pip/issues/9069>`_) Features -------- - Add ``--exclude`` option to ``pip freeze`` and ``pip list`` commands to explicitly exclude packages from the output. (`4256 <https://github.com/pypa/pip/issues/4256>`_) - Allow multiple values for --abi and --platform. (`6121 <https://github.com/pypa/pip/issues/6121>`_) - Add option ``--format`` to subcommand ``list`` of ``pip cache``, with ``abspath`` choice to output the full path of a wheel file. (`8355 <https://github.com/pypa/pip/issues/8355>`_) - Improve error message friendliness when an environment has packages with corrupted metadata. (`8676 <https://github.com/pypa/pip/issues/8676>`_) - Make the ``setup.py install`` deprecation warning less noisy. We warn only when ``setup.py install`` succeeded and ``setup.py bdist_wheel`` failed, as situations where both fails are most probably irrelevant to this deprecation. (`8752 <https://github.com/pypa/pip/issues/8752>`_) - Check the download directory for existing wheels to possibly avoid fetching metadata when the ``fast-deps`` feature is used with ``pip wheel`` and ``pip download``. (`8804 <https://github.com/pypa/pip/issues/8804>`_) - When installing a git URL that refers to a commit that is not available locally after git clone, attempt to fetch it from the remote. (`8815 <https://github.com/pypa/pip/issues/8815>`_) - Include http subdirectory in ``pip cache info`` and ``pip cache purge`` commands. (`8892 <https://github.com/pypa/pip/issues/8892>`_) - Cache package listings on index packages so they are guarenteed to stay stable during a pip command session. This also improves performance when a index page is accessed multiple times during the command session. (`8905 <https://github.com/pypa/pip/issues/8905>`_) - New resolver: Tweak resolution logic to improve user experience when user-supplied requirements conflict. (`8924 <https://github.com/pypa/pip/issues/8924>`_) - Support Python 3.9. (`8971 <https://github.com/pypa/pip/issues/8971>`_) - Log an informational message when backtracking takes multiple rounds on a specific package. (`8975 <https://github.com/pypa/pip/issues/8975>`_) - Switch to the new dependency resolver by default. (`9019 <https://github.com/pypa/pip/issues/9019>`_) - Remove the ``--build-dir`` option, as per the deprecation. (`9049 <https://github.com/pypa/pip/issues/9049>`_) Bug Fixes --------- - Propagate ``--extra-index-url`` from requirements file properly to session auth, so that keyring auth will work as expected. (`8103 <https://github.com/pypa/pip/issues/8103>`_) - Allow specifying verbosity and quiet level via configuration files and environment variables. Previously these options were treated as boolean values when read from there while through CLI the level can be specified. (`8578 <https://github.com/pypa/pip/issues/8578>`_) - Only converts Windows path to unicode on Python 2 to avoid regressions when a POSIX environment does not configure the file system encoding correctly. (`8658 <https://github.com/pypa/pip/issues/8658>`_) - List downloaded distributions before exiting ``pip download`` when using the new resolver to make the behavior the same as that on the legacy resolver. (`8696 <https://github.com/pypa/pip/issues/8696>`_) - New resolver: Pick up hash declarations in constraints files and use them to filter available distributions. (`8792 <https://github.com/pypa/pip/issues/8792>`_) - Avoid polluting the destination directory by resolution artifacts when the new resolver is used for ``pip download`` or ``pip wheel``. (`8827 <https://github.com/pypa/pip/issues/8827>`_) - New resolver: If a package appears multiple times in user specification with different ``--hash`` options, only hashes that present in all specifications should be allowed. (`8839 <https://github.com/pypa/pip/issues/8839>`_) - Tweak the output during dependency resolution in the new resolver. (`8861 <https://github.com/pypa/pip/issues/8861>`_) - Correctly search for installed distributions in new resolver logic in order to not miss packages (virtualenv packages from system-wide-packages for example) (`8963 <https://github.com/pypa/pip/issues/8963>`_) - Do not fail in pip freeze when encountering a ``direct_url.json`` metadata file with editable=True. Render it as a non-editable ``file://`` URL until modern editable installs are standardized and supported. (`8996 <https://github.com/pypa/pip/issues/8996>`_) Vendored Libraries ------------------ - Fix devendoring instructions to explicitly state that ``vendor.txt`` should not be removed. It is mandatory for ``pip debug`` command. Improved Documentation ---------------------- - Add documentation for '.netrc' support. (`7231 <https://github.com/pypa/pip/issues/7231>`_) - Add OS tabs for OS-specific commands. (`7311 <https://github.com/pypa/pip/issues/7311>`_) - Add note and example on keyring support for index basic-auth (`8636 <https://github.com/pypa/pip/issues/8636>`_) - Added initial UX feedback widgets to docs. (`8783 <https://github.com/pypa/pip/issues/8783>`_, `8848 <https://github.com/pypa/pip/issues/8848>`_) - Add ux documentation (`8807 <https://github.com/pypa/pip/issues/8807>`_) - Update user docs to reflect new resolver as default in 20.3. (`9044 <https://github.com/pypa/pip/issues/9044>`_) - Improve migration guide to reflect changes in new resolver behavior. (`9056 <https://github.com/pypa/pip/issues/9056>`_) ``` </details> <details> <summary>Links</summary> - PyPI: https://pypi.org/project/pip - Changelog: https://pyup.io/changelogs/pip/ - Homepage: https://pip.pypa.io/ </details> Co-authored-by: pyup-bot <[email protected]> Co-authored-by: Ellen Marie Dash <[email protected]>

triage-new-issues bot added the S: needs triage Issues/PRs that need to be triaged label Jun 17, 2020

nlhkabu mentioned this issue Jun 24, 2020

Help users determine the origin of their ResolutionImpossible error #8492

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nlhkabu mentioned this issue Jun 24, 2020

Add resolver docs #8493

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nlhkabu added C: new resolver UX User experience related and removed S: needs triage Issues/PRs that need to be triaged labels Jun 24, 2020

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pradyunsg closed this as completed in #8493 Jul 9, 2020

brainwane mentioned this issue Jul 30, 2020

pip 20.2 release (Q3 2020) #8511

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Write documentation for ResolutionImpossible error message #8459

Write documentation for ResolutionImpossible error message #8459

nlhkabu commented Jun 17, 2020 •

edited

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Fixing conflicting dependencies

Understanding your error message

Error causes

1. Your "top level" requirements are too strict

2. A package that you are using has requirements that are too strict

3. All requirements are loose, but a solution does not exist

Overriding dependency resolution (force installing)

Fixing conflicting dependencies

Understanding your error message

Error causes

1. Your "top level" requirements are too strict

2. A package that you are using has requirements that are too strict

3. All requirements are loose, but a solution does not exist

Overriding dependency resolution (force installing)

Fixing conflicting dependencies

Understanding your error message

Error causes

1. Your "top level" requirements are too strict

2. A package that you are using has requirements that are too strict

3. All requirements are loose, but a solution does not exist

Getting help

Fixing conflicting dependencies (v. 17 June)

Understanding your error message

Determining the origin of your conflict

1. Conflicts in your downstream dependencies

2. Conflicts between your top level requirements and your downstream dependencies

Possible solutions

1. Audit your top level requirements

2. Loosen your top level requirements

3. Loosen the requirements of your downstream dependencies

4. All requirements are loose, but a solution does not exist

Getting help

nlhkabu commented Jun 17, 2020

Write documentation for ResolutionImpossible error message #8459

Write documentation for ResolutionImpossible error message #8459

Comments

nlhkabu commented Jun 17, 2020 • edited Loading

Fixing conflicting dependencies

Understanding your error message

Error causes

1. Your "top level" requirements are too strict

2. A package that you are using has requirements that are too strict

3. All requirements are loose, but a solution does not exist

Overriding dependency resolution (force installing)

Fixing conflicting dependencies

Understanding your error message

Error causes

1. Your "top level" requirements are too strict

2. A package that you are using has requirements that are too strict

3. All requirements are loose, but a solution does not exist

Overriding dependency resolution (force installing)

Fixing conflicting dependencies

Understanding your error message

Error causes

1. Your "top level" requirements are too strict

2. A package that you are using has requirements that are too strict

3. All requirements are loose, but a solution does not exist

Getting help

Fixing conflicting dependencies (v. 17 June)

Understanding your error message

Determining the origin of your conflict

1. Conflicts in your downstream dependencies

2. Conflicts between your top level requirements and your downstream dependencies

Possible solutions

1. Audit your top level requirements

2. Loosen your top level requirements

3. Loosen the requirements of your downstream dependencies

4. All requirements are loose, but a solution does not exist

Getting help

nlhkabu commented Jun 17, 2020

nlhkabu commented Jun 17, 2020 •

edited

Loading