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

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.

[uranusjr]

@MohsenAAkeel Use this instead

from pip._internal.utils.compat import WINDOWS