Python's os.walk() fails in Windows when there are long filenames

Question

I use python os.walk() to get files and dirs in some directories, but there're files whose names are too long(>300), os.walk() return nothing, use onerror I get '[Error 234] More data is available'. I tried to use yield, but also get nothing and shows 'Traceback: StopIteration'.

OS is windows, code is simple. I have tested with a directory, if there's long-name file, problem occur, while if rename the long-name files with short names, code can get correct result.

I can do nothing for these directories, such as rename or move the long-name files. Please help me to solve the problem!

def t(a):
  for root,dirs,files in os.walk(a): 
    print root,dirs,files
t('c:/test/1')

I wonder what operating system lets you have name files that long. — PepperoniPizza, Aug 02 '13 at 15:04
Can you provide us with some more details? What os are you using, and can you show us a minimal version of your code that demonstrates the problem? — larsks, Aug 02 '13 at 15:05
windows, code simple, no any special: for root,dirs,files in os.walk(...): print root . I have tested, if rename the long-name files with short names, code can get correct result. — user2646309, Aug 02 '13 at 15:20
I'm just reiterating what @larsks said, we need to see a minimal version of your code to help diagnose your problem! — Hooked, Aug 02 '13 at 15:25

score 5 · Accepted Answer · edited May 23 '17 at 12:31

5

In Windows file names (including path) can not be greater than 255 characters, so the error you're seeing comes from Windows, not from Python - because somehow you managed to create such big file names, but now you can't read them. See this post for more details.

edited May 23 '17 at 12:31

Community

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answered Aug 02 '13 at 15:38

Óscar López

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When use os.walk(), how to ignore long-name files and get other files and dirs whose names not long? – user2646309 Aug 02 '13 at 15:44
I tried some file-search tools, they can't find long-name files but can find all other files in the same directory! – user2646309 Aug 02 '13 at 15:47
I have tried catch exception using try..except..., but useless – user2646309 Aug 02 '13 at 15:48

score 0 · Answer 2 · answered Jan 27 '22 at 23:52

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The only workaround I can think of is to map the the folder to the specific directory. This will make the path way shorter. e.g. z:\myfile.xlsx instead of c:\a\b\c\d\e\f\g\myfile.xlsx

answered Jan 27 '22 at 23:52

Chadee Fouad

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Ooker · Answer 3 · 2023-04-30T07:22:26.237

The limitation for maximum length for a path is 256. Starting in Windows 10, version 1607, this limitation have been removed, but you have to opt-in to this new behavior. You can either do one of these:

Open registry, navigate to Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem\, and create a new key with the name LongPathsEnabled, type REG_DWORD and value 1. 2
In PowerShell command New-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem" -Name "LongPathsEnabled" -Value 1 -PropertyType DWORD -Force

Read more about how Windows naming files, paths and namespaces here.

Or you can run a virtual machine using an Unix OS.

Python's os.walk() fails in Windows when there are long filenames

3 Answers3