Obscure error message when installing wheels with long filenames on Windows with LongPathsEnabled set to 0

[ogrisel]

Description

As documented in our troubleshooting guide, some Windows users experience an obscure error message such as:

C:\Users\username>C:\Users\username\AppData\Local\Microsoft\WindowsApps\python.exe -m pip install scikit-learn
Collecting scikit-learn
...
Installing collected packages: scikit-learn
ERROR: Could not install packages due to an EnvironmentError: [Errno 2] No such file or directory: 'C:\\Users\\username\\AppData\\Local\\Packages\\PythonSoftwareFoundation.Python.3.7_qbz5n2kfra8p0\\LocalCache\\local-packages\\Python37\\site-packages\\sklearn\\datasets\\tests\\data\\openml\\292\\api-v1-json-data-list-data_name-australian-limit-2-data_version-1-status-deactivated.json.gz'

https://scikit-learn.org/stable/install.html#error-caused-by-file-path-length-limit-on-windows

This happens because under Windows, file paths are limited to 260 characters by default.

Expected behavior

When such an error OSError or EnvironmentError with No such file or directory, parse the file path and check if its length could explain the problem.

If this is the case, enrich the error message to point the user to use regedit to set LongPathsEnabled to 1 as we do in the scikit-learn documentation linked above.

pip version

unknown

Python version

does not matter

OS

Windows

How to Reproduce

I suppose it's possible to create a venv into a deeply nested folder with more than 200 characters and then install wheel package with long filenames in it (pip install scikit-learn==0.24.2 should do).

I am not 100% sure because I have no Windows machine handy.

Output

See above.

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[uranusjr]

Unfortunately there really isn’t a good solution to this. Windows emits FileNotFoundError for a ton of things, and the path length limit is only one of it. There really isn’t a way to realiably pinpoint the reason. The best pip can do IMO would be to do a len() and suggest maybe you need to enable long paths when the result is over the limit.

[ogrisel]

The best pip can do IMO would be to do a len() and suggest maybe you need to enable long paths when the result is over the limit.

+1 for doing a len() on the exception error message (since it includes the file path).

[uranusjr]

For aspiring contributors: This needs to be handled in the except OSError block in InstallCommand.run() (pip/_internal/commands/install.py). The function is a monster, so some refactoring en passant may make sense as well.

[OBITORASU]

except OSError as error:
    show_traceback = (self.verbosity >= 1)

    message = create_os_error_message(
        error, show_traceback, options.use_user_site,
    )

Will adding a check for the kernel (NT in this case) using os.name after the above snippet and then using an if statement to trigger a logger.warning warning the user in case the error (error message) is above a certain length do the job?

[MohsenAAkeel]

I was taking a look at this as well (saw first issue tag). I think sys.platform would be a better method of checking what OS the user is running as os.name is good for checking posix compliance.

[uranusjr]

@MohsenAAkeel Use this instead

from pip._internal.utils.compat import WINDOWS

[pradyunsg]

Resolved by #10046.

FYI @OBITORASU -- GitHub need "Fixes ..." to trigger autoclosing, so "Fixes Issue ..." didn't work. :)

[OBITORASU]

Resolved by #10046.

FYI @OBITORASU -- GitHub need "Fixes ..." to trigger autoclosing, so "Fixes Issue ..." didn't work. :)

I will keep that in mind from next time on, thanks for the heads up! ^-^