Microsoft and the unfixed ReFS bug in Windows

Windows[German]Microsoft's patchday is on February 8, 2022 again. However, those who hope that certain things will be fixed with the security updates on February 8 after the disaster with the January 2022 patchday might be disappointed. At least that probably applies to the ReFS issue, which leaves the corresponding volumes as RAW in certain scenarios. In the meantime, I have a technical explanation why the out-of-date updates do not bring any improvement in some scenarios. Whether Microsoft will ever fix this is still unanswered.


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What is the ReFS problem?

If the January 11, 2022 security updates were installed, there was the problem that disks formatted with ReFS would only show up as RAW. I had addressed this in the blog post Microsoft patch day issues Jan. 2022: bugs confirmed, but updates not pulled. There, however, the text referred to the installation of updates KB5009624 (Monthly Rollup for Windows 8.1 and Windows Server 2012 R2) and Update KB5009595 (Security Only Quality Update for Windows 8.1 and Windows Server 2012 R2). Users suddenly lack support for the ReFS file system.

Microsoft had then released out-of-band updates on January 17 and 18, 2022, to bring back the missing ReFS support for the respective Windows version. The relevant support postings state:

Fixes an issue that can prevent removable media formatted with the robust file system (ReFS) from being recovered or cause the removable media to be deployed in RAW file format. This issue occurs after installing the January 11, 2022 Windows update.

I've pulled out a list of all the slout-of-band updates that claim to fix the ReFS problem below.

Comments like this one confirm that ReFS drives can be mounted again. However, there are inconsistencies as users report that ReFS support is still missing for certain scenarios. I had only partially reported on this in the blog post Out-of-Band Updates for Windows (Jan. 17/18, 2022) doesn't fixes ReFS Issues complete.

ReFS 1.0 problem is not fixed

While there was hope that the problems with ReFS after the January 2022 patchday mentioned above were only temporary, that hope has now dissipated in my eyes. Mike already posted  in January 2022 this comment and referred to the Techcommunity discussion ReFS volume appears RAW (version doesn't match expected value) after Windows Update. There, it also revolves around the January 2022 security updates breaking support for the ReFS file system. In the discussion, British Microsoft employee Stephen Cole (stephc_msft) got in touch and writes in his comment:


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The main issue is there are various versions of REFS:

ReFS v1 as used on Server 2012R2 and ReFS v3 used on later OS's

The Updated fix, for Refs on removable drives, only addresses the ReFS v3 case and does not (and never will) address the refsv1 case.
Note that some disks, even on later OS's might be using ReFS v1 if they were originally set up on earlier systems

And so the fix will not help on those disks on those systems

Since its mainly VMWare VM's that are affected, as they consider hotplug disks as removable, suggest using the vmware devices.hotplug solution described earlier

You can check the Refs version with

fsutil fsinfo refsinfo x:

(although cant do this if the drive is currently showing as RAW)

In a nutshell: There is ReFS v1 on Windows Server 2012 R2 and ReFS v3 in later Windows versions. The out-of-band updates mentioned above only address ReFS v3 for removable media. Those using ReFS v1 on drives will be out of luck after the January 2022 security update. Affected VMware users can disable hotplugging (see Status of January 2022 security updates from Microsoft (2022/01/25)).

In the Techcommunity discussion ReFS volume appears RAW (version doesn't match expected value) after Windows Update, those affected also confirm that volumes with ReFS v1.2 would appear as RAW, while volumes with ReFS v3.4 probably work again. This means that systems virtualized under Windows Server 2012 R2 no longer get real ReFS support.

Those using ReFS v1 volumes on Windows Server 2016 or later can only work around the problem by creating new disks with this file system or reformatting the old ReFS volumes. It gets difficult for users working with Windows Server 2012 R2, since ReFS sv3 is not supported there. Those who virtualize with VMware there have to choose the solution mentioned above and disable hotplug.

Addendum: Blog reader Karl has pointed me to this GitHub documentation, that describes the available ReFS versions.

Similar articles:
Patchday: Windows 8.1/Server 2012 R2 Updates (January 11, 2022), boot loop reported
Patchday: Windows 10 Updates (January 11, 2022)
Patchday: Windows 11 Updates (January 11, 2022)
Patchday: Updates for Windows 7/Server 2008 R2 (January 11, 2022)

Windows Server: January 2022 security updates are causing DC boot loop
Windows VPN connections (L2TP over IPSEC) broken after January 2022 update
Windows Server 2012/R2: January 2022 Update KB5009586 bricks Hyper-V Host
Microsoft patch day issues Jan. 2022: bugs confirmed, but updates not pulled

Microsoft Microsoft Januar 2022 Patchday Revisions (2022/01/14)
Windows Out-of-band Updates fixes Jan. 2022 patch day issues (Jan. 17, 2022)
Windows 10/Server: Out-of-band Updates fixes Jan. 2022 patch day issues (Jan. 17, 2022)
Out-of-band Updates for Windows Server 2019 fixes Jan. 2022 Patch day issues (Jan. 18, 2022)
Windows 7/8.1; Server 2008R2/2012R2: Out-of-band Updates with Fixes for Jan. 2022 Patch day Issues (2022/01/17)

Review: Fix for Windows IPSec VPN Connection Issues
Out-of-Band Updates for Windows (Jan. 17/18, 2022) doesn't fixes ReFS Issues complete
Review: Fix for Hyper-V Host Startup Problem in Windows (January 2022)
Status of January 2022 security updates from Microsoft (2022/01/25)


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5 Responses to Microsoft and the unfixed ReFS bug in Windows

  1. jm says:

    Hello, I think the article is inaccurate:
    Specifically part: "Those using ReFS v1 volumes on Windows Server 2016 or later can only work around the problem"

    Because REFS is auto upgraded and not backward compatible. So if you mount REFS from 2012 in 2016, filesystem version is upgraded and REFS is no longer readable in 2012 ( info for example https://techcommunity.microsoft.com/t5/windows-server-for-it-pro/refs-volume-auto-updated/m-p/293297 )

    • guenni says:

      But 99% of the victims are not affected by this ReFS upgrade thing. They install the update, the drive isn't available. They uninstall the updates, the drive is back.

      BTW: Verry helpful, your link to the techcommunity discussion. Will link it also within the German blog post

    • Thomas says:

      This is not totally correct.

      I have a ReFS volume originally created in 2012 R2, now mounted in server 2016.

      I did fsutil fsinfo refsinfo x: on 2016 and the ReFS version still remains as v1.2.

      Only new ReFS volumes formatted fresh out of server 2016 will be v3.x.

  2. Adam S says:

    Thank you for the article. It's disappointing but I'm thankful you've written this up.
    As I'm running a Server 2012 R2 environment with a volley of external ReFS formatted disks, I'll have to halt Windows Updates until I can upgrade to 2016 (which will mean a new server).

  3. BR says:

    Thx 4 article. At the day before yesterday, imma formatted my new ssd at ReFS, and after 1 day i seen RAW on at my fresh-installed Win 11 with last updates :/

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