Long paths not working in windows 2019

Question

Followed the steps given below to enable long paths and rebooted the machine

1. Press Win + R keys on your keyboard and type regedit then press Enter. Registry Editor will be opened.
2. Go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem.
3. Edit LongPathsEnabled and set it to 1.
4. Press Win + R keys on your keyboard and type gpedit.msc then press Enter. Group Policy Editor will be opened.
5. Go to Local Computer Policy -> Computer Configuration -> Administrative Templates -> System -> Filesystem, then enable the Enable Win32 long paths option.
   6.Restart machine.

Executed the below program to check if the file gets created in the already existing folder structure C:\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz

---

int main()
{
HANDLE h = CreateFileA(
"C:\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\abcdefghijklmnopqrstuvwxyz\012345678901234567890123456789.txt",
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
CREATE_NEW,
FILE_ATTRIBUTE_TEMPORARY,
NULL);

if (h == INVALID_HANDLE_VALUE) { DWORD err = GetLastError(); printf("err %dn", err); getchar(); return 1; }
printf("Created\n");
getchar();

return 0;
}

---

The above program failed to create the file and produced the following output
err 3

The same program worked in windows 2016

What additional thing needs to be done in windows 2019 for long paths to work?

Machine details
Windows server 2019
Microsoft windows Server
Version 1809 (OS build 17763.316)

Answer 1

Hi there,

If this works on Windows 2016 it should work on Windows 2019 too. You might have configured them wrong or defined the long path differently. You can try the Powershell command and see if that helps you.

New-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem" `
-Name "LongPathsEnabled" -Value 1 -PropertyType DWORD -Force

Also note the maximum path of 32,767 characters is approximate, because the "\?\" prefix may be expanded to a longer string by the system at run time, and this expansion applies to the total length.

Maximum Path Length Limitation
https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=powershell

---

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Answer 2

I tested on Windows 10 and I got the same error (3)
But it worked by using :

  HANDLE h = CreateFileW(L"\\\\?\\C:\\abcdefghijklmnopqrstuvwxyz\\abcdefghijklmnopqrstuvwxyz\\abcdefghijklmnopqrstuvwxyz\\abcdefghijklmnopqrstuvwxyz\\abcdefghijklmnopqrstuvwxyz\\abcdefghijklmnopqrstuvwxyz\\abcdefghijklmnopqrstuvwxyz\\abcdefghijklmnopqrstuvwxyz\\abcdefghijklmnopqrstuvwxyz\\012345678901234567890123456789.txt",
            

Answer 3

from the documentation:
"These are the file management functions that no longer have MAX_PATH restrictions if you opt-in to long path behavior: CopyFileW, CopyFile2, CopyFileExW, CreateFileW, CreateFile2, CreateHardLinkW, CreateSymbolicLinkW, DeleteFileW, FindFirstFileW, FindFirstFileExW, FindNextFileW, GetFileAttributesW, GetFileAttributesExW, SetFileAttributesW, GetFullPathNameW, GetLongPathNameW, MoveFileW, MoveFileExW, MoveFileWithProgressW, ReplaceFileW, SearchPathW, FindFirstFileNameW, FindNextFileNameW, FindFirstStreamW, FindNextStreamW, GetCompressedFileSizeW, GetFinalPathNameByHandleW."

as you can see: CreateFileA is not in the list.
in fact: not one of them is the ANSI version.
so if CreateFileA ever worked for you (which I still somehow doubt. Perhaps you added the "\?\" prefix?) you relied on undocumented behavior.