"Enable Win32 Long Paths" GPO

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Hey,
does anyone has experiences with the Win32 Long Paths GPO?
Is there anything to be aware of? Does this work instantly for all attached storage?

And a general question. If I add a GPO to a OU which includes Win2016 and Win2012 server. Will the 2012 server just ignore this GPO? Or should I better add a new GPO just for the 2016 servers?

Thanks!

Shifty,

I hope all is well. Great question ! Not as simple on the surface as one would think. Let's take a look at how to address this by starting out with some basic information that provides context:

By default, the maximum path length limit in Windows is 260 characters. A local path is structured in the following order:

Drive letter, colon, backslash, name components separated by backslashes, and a terminating null character.

Starting with Windows 10 build 14352, you can enable NTFS long paths to allow MANIFESTED win32 applications and Windows Store applications to access paths beyond the normal 260 characters limit per node.

Enabling this setting will cause the long paths to be accessible within the process.

Starting with Windows build 1607, this policy has moved and is now called Win32 long paths.

You must be signed in as an administrator to be able to enable or disable Win32 long paths.

Enabling NTFS (Win32) long paths will allow manifested win32 applications and Windows Store applications to access paths beyond the normal 260 character limit per node on file systems that support it. Enabling this setting will cause the long paths to be accessible within the process.

This actually means that an application has to have the following line in its manifest:

<longPathAware>true</longPathAware>

A manifest is a small file that contains additional information about the process EXE such as compatibility information and DPI-awareness etc...

NOTE: The description of the group policy says:
Enabling Win32 long paths will allow manifested win32 applications and Windows Store applications to access paths beyond the normal 260 character limit per node on file systems that support it. ...

The "manifested" attribute in the description means that only win32 applications that are designed to use long paths, will use that feature after you enable the policy.

In other words, applications that DO NOT have the manifest attribute declared/defined as noted above WILL NOT be able to utilize this policy.

There are 2 options to enable the support: Group Policy & Registry Editing.

The GPO option is shown below. You need to use the Local Computer Policy editor and follow the arrows to enable.

If you want to use the Registry Editing option, do the following:

The .reg files below will add and modify the dword value in the registry key below.

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem

LongPathsEnabled dword

(delete) = disable
1 = Enable

Now, if you want to get around this, check out the following:

Windows Explorer (File Explorer) does not support filenames longer than 260 characters, and does not currently support paths to a folder longer than 248 characters.

This is by design, and locked in due to some API requirements related to the "MAX_PATH" variable.

The group policy setting or registry setting mentioned above will not change this, but there is a workaround.

If this is a local windows path you can use the "subst" command to mount a virtual network drive

1. Open a command prompt
2. Run the command: "subst x: C:*really long path*
3. Next use File Explorer to browse to the X:\ drive
4. Delete, move or rename them as needed
5. Run "subst x: /D" to delete the shortcut substitution

If the file is on a remote server you can mount a directory into the path to get around the limitation

1. Open a command prompt
2. Run the command: "net use x: \SERVER\SHARE*long path*
3. Next use File Explorer to browse to the X:\ drive
4. Delete, move or rename them as needed
5. Run "net use x: /delete" to delete the network drive once you're done

So, not so simple, but with a little planning, may be of use to you, as long as you take note of the MINIMUM O/S version support for the policy and the fact that a Win32 app would need to be manifested to allow for the long file support to work.

The general question that you asked about the application of the GPO to an OU with mixed O/S servers is actually very straightforward, as the Win2012 servers will simply ignore the policy, as the setting does not apply to them.

Hope that helps. If I can be of any additional assistance, please let me know.

Good Luck !!

Cheers,

Adam

@adam-gordon

Hi Adam, thanks for the awesome answer. This helps a lot!