What version of MS Operating Systems support the long file path feature \\?\

malcolm29 used Ask the Experts™
I am trying to read in file names that have paths longer than 266 characters.  So, I'm using \\?\ as a pre-pend to the file name.

This works great on my Windows 10 machine, but when I try to run it (using PowerShell v. 4) on a Windows Server 2012 R2 Datacenter machine (Windows version 6.3.9600), I get error messages leading me to assume that the feature is not supported.

Here's my actual PowerShell code to test this.  Again, this works fine on my Win10 desktop, but not the server:
$sFileName = "\\?\H:\COMMUNITY\Compliance\AQIP\2010 Systems Portfolio\Systems Portfolio Draft orig (Autosaved).docx"
$objFileStream = New-Object IO.FileStream($sFileName,[System.IO.FileMode]::Open)

The error I get is:
New-Object : Exception calling ".ctor" with "2" argument(s): "Illegal characters in path."
At H:\Information Technology\InstallFilesOld\OtherPSScripts\Test.ps1:2 char:18
+ $objFileStream = New-Object IO.FileStream("\\?\$($sFileName)",[System.IO.FileMod ...
+                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (:) [New-Object], MethodInvocationException
    + FullyQualifiedErrorId : ConstructorInvokedThrowException,Microsoft.PowerShell.Commands.NewObjectCommand

If I run the code without the \\?\ (using the following code), I don't get any errors.
$sFileName = "H:\COMMUNITY\Compliance\AQIP\2010 Systems Portfolio\Systems Portfolio Draft orig (Autosaved).docx"
$objFileStream = New-Object IO.FileStream($sFileName,[System.IO.FileMode]::Open)
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Senior Network Consultant / Engineer
This is actually a .NET Framworks issue. .NET 4.6.2 is what enables this functionality. More info:

Make sure you have .NET 4.6.2 or newer installed and then test out your code.


Great!  Thanks, Jeremy!  Greg.
Jeremy WeisingerSenior Network Consultant / Engineer

Glad to help. :)

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