Re: os.scandir problem

Op 31/03/2026 om 9:48 schreef Anders Munch:
> Rob Cliffe via Python-list<[email protected]>  wrote:
> > When the RAM disc is empty,
> >      os.scandir("R:")
> > raises a FileNotFoundError instead of (as I would have expected) returning an empty iterator.
>
> os.scandir is a simple wrapper around FindFirstFile/FindNextFile.  If FindFirstFileW("R:", "*.*") sets the file-not-found Windows error code, then that will be turned into the exception that you see.
I can confirm this. I wrote a small test directly using FindFirstFileW() 
(in C++, though you could do it in Python using ctypes), with the 
following result:
(Z is an empty RAM disk, EmptyDir is a regular empty directory on my 
hard disk, D is an empty flash drive)

Z:               ERROR_FILE_NOT_FOUND
Z:\              ERROR_FILE_NOT_FOUND
Z:\*.*           ERROR_FILE_NOT_FOUND
EmptyDir         OK
EmptyDir\        ERROR_INVALID_PARAMETER
EmptyDir\*.*     OK
D:               ERROR_FILE_NOT_FOUND
D:\              ERROR_FILE_NOT_FOUND
D:\*.*           OK

There doesn't seem to be much consistency.
As you can see, FindFirstFileW() on an empty RAM disk gives an 
ERROR_FILE_NOT_FOUND. Adding \ or \*.*. Doesn't help.
Weirdly enough adding \*.* does help for the empty flash drive.
> You might want to try os.scandir("R:\\").  Your issue could have something to do with the current directory for the R: drive not being well-defined.
>
I tried it; doesn't make a difference.

I think your best bet is to simply handle the FileNotFoundError 
exception manually in your code. Perhaps best to write your own wrapper 
around os.scandir() that does that.

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