On Windows, shutil.rmtree() uses the path-based implementation, which builds the full path of every file and directory. Unless long paths are enabled in the registry (LongPathsEnabled, off by default), paths longer than MAX_PATH (260 characters) cannot be accessed. os.walk() ignores the resulting FileNotFoundError, so the deep part of the tree is silently skipped, and rmtree() then fails with "The directory is not empty".

import os, shutil
path = '\\\\?\\' + os.path.abspath('deep')
os.mkdir(path)
for i in range(200):
    path += '\\d'
    os.mkdir(path)
shutil.rmtree('deep')

OSError: [WinError 145] The directory is not empty: 'deep\\d\\d\\d\\...'

Using extended-length paths (\\?\C:\...) will help, but as a side effect they can leak to the user via errors.

Linked PRs

• gh-159681: Fix shutil.rmtree() for paths longer than MAX_PATH on Windows #159699