Windows: OSError: [Errno 22] Invalid argument when trying to open a file with filename length >= 256 #130542
Description
Bug report
Bug description:
Tested with:
- Microsoft Windows 10 Pro [10.0.19045 N/A Build 19045]
- Python version: 3.13.0rc2 (main, Sep 9 2024, 20:49:38) [MSC v.1929 64 bit (AMD64)]
LongPathsEnabledalready enabled in registry- NTFS filesystem
The problem is not about the length of the full file path (you can easily pass 500+ without any issue), but the filename.
import sys
import os
print('Python version:', sys.version)
if not os.path.exists('D:\\' + 'f' * 200):
os.mkdir('D:\\' + 'f' * 200)
p1 = "D:\\" + 'f' * 200 + '\\' + 'a' * 200
print(len(p1))
open(p1, 'w').write('')
p2 = "D:\\" + 'f' * 200 + '\\' + 'a' * 255
print(len(p2))
open(p2, 'w').write('')
p3 = "D:\\" + 'f' * 200 + '\\' + 'a' * 256
print(len(p3))
open(p3, 'w').write('')>bug
Python version: 3.13.0rc2 (main, Sep 9 2024, 20:49:38) [MSC v.1929 64 bit (AMD64)]
404
459
460
Traceback (most recent call last):
File "D:\long\bug.py", line 19, in <module>
open(p3, 'w').write('')
~~~~^^^^^^^^^
OSError: [Errno 22] Invalid argument: 'D:\\ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff\\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa'
As you can see, Python throws a random OSError: [Errno 22] Invalid argument when filename is 256-character long.
I also tried to use R'\\?\D:\', does not help.
CPython versions tested on:
3.14
Operating systems tested on:
Windows