Microsoft has released KB5089573, an optional non-security preview update for Windows 11 versions 24H2 and 25H2, on May 26, 2026. The update moves systems to a higher OS build number and introduces quality improvements, but it’s arriving with a clear caveat from experienced administrators: don’t push this out broadly without first piloting it on a limited set of devices. Reports of a recurring EFI system partition error (0x800f0922) and other deployment snags underscore the need for a cautious, ring-based rollout strategy.

What’s inside KB5089573: a classic “C” week preview

KB5089573 follows the familiar pattern of Microsoft’s “C” week optional updates—non-security cumulative previews that ship in the third or fourth week of the month. These previews let organizations test upcoming fixes and features before they become mandatory in the next Patch Tuesday release. For May 2026, the update targets the two most recent feature updates: Windows 11 24H2 (originally released in Q4 2024) and Windows 11 25H2 (released earlier in 2026).

After installation, build numbers increment to 26100.xxxx (for 24H2) and 26200.xxxx (for 25H2), though the exact revisions depend on whether your device is in the General Availability channel or running an elevated build. The update brings quality-of-life improvements across the OS, including fixes for File Explorer freezes, Start menu reliability tweaks, and enhanced performance for certain DirectStorage workloads. It also aligns with Microsoft’s continued push to refine the user experience on Copilot+ PCs, with under-the-hood optimizations for Neural Processing Unit (NPU) offloading.

Crucially, KB5089573 includes a servicing stack update (SSU) that updates the component responsible for installing Windows updates. This SSU is required to ensure future updates install smoothly, but it also means that any failure during KB5089573’s own installation can corrupt the servicing stack, leaving the system unable to receive patches without manual intervention.

The EFI system partition error: 0x800f0922 returns

One of the most discussed issues linked to KB5089573, based on early adopter feedback in Windows forum discussions, is a known error code 0x800f0922. This error typically points to inadequate free space on the EFI system partition—a small, hidden partition that stores the Windows Boot Manager and critical boot files. Many OEM Windows installations ship with a tiny EFI partition (often 100MB or less), which can fill up when cumulative updates try to stage new boot files or language resources.

When KB5089573 fails with 0x800f0922, the system rolls back the update, but the attempt can leave behind redundant files that further clog the EFI partition. On some devices, users have reported that subsequent attempts fail until they manually resize the EFI partition using third-party tools or command-line diskpart utilities. This is not a new problem—Microsoft documented a similar issue with KB5034441 back in 2024—but KB5089573 appears to have re-triggered the fault on machines that had never previously encountered it.

Administrators on several IT forums are recommending a pre-flight check: open Disk Management or run echo list volume | diskpart to verify that the EFI partition has at least 250MB of free space before attempting to install KB5089573. For machines that fall short, resizing the partition ahead of time prevents the error and avoids a time-consuming recovery later.

Other known issues: audio glitches, print drivers, and virtualization

Beyond the EFI partition woes, KB5089573’s known issues page (which Microsoft published alongside the release) flags a handful of additional problems:

  • Audio playback disruption: Devices using certain USB audio DACs may experience intermittent dropouts after the update. A temporary workaround involves disabling audio enhancements in Sound Control Panel. Microsoft says a full fix will arrive in the June 2026 Patch Tuesday update.
  • Print driver conflicts: Some older Type 3 printer drivers, particularly from Xerox and Ricoh, can cause the Print Spooler service to crash after KB5089573 is installed. The issue manifests as a “The local print spooler service is not running” error. Affected organizations can mitigate by switching to Type 4 drivers or pausing the rollout for print servers.
  • Hyper-V virtual machine startup delays: On hosts with Gen 2 VMs, some environments see a 30–60 second delay when starting virtual machines after this update. Microsoft attributes this to a change in how Hyper-V handles Secure Boot trust validation and expects a permanent fix in the next optional update.

These known issues, while not as widespread as the EFI partition error, further strengthen the case for a measured, pilot-first deployment approach.

The deployment imperative: pilot rings are not optional in 2026

IT administrators have long used deployment rings to manage Windows updates, but the pace of change in Windows 11—coupled with the increasing complexity of optional previews—means that skipping the pilot phase is riskier than ever. KB5089573 illustrates this perfectly: a combination of a mandatory SSU, an EFI partition dependency that isn’t checked by the installer, and new driver-side quirks makes blanket deployment a gamble.

Experienced admins recommend a three-ring model for a preview update like this:

  1. Canary/Test ring (Day 1–2): Push KB5089573 to a handful of IT-owned, non-critical devices representing your hardware diversity—different OEMs, disk configurations, and peripheral setups. Monitor for the 0x800f0922 error, audio issues, and print spooler crashes. Use Windows Update for Business reports or Microsoft Intune to check for failures.

  2. Early adopter ring (Day 3–7): Expand to a wider group that includes some power users or departments that can tolerate minor disruption. Collect feedback through a simple Microsoft Forms survey or a dedicated Teams channel. If the EFI partition error surfaces on more than 2–3% of machines, halt the rollout and plan manual remediation.

  3. Broad production ring (Week 2): Only after at least 10 days with no unresolved showstoppers should you approve KB5089573 for the general population. Even then, enable a gradual rollout in your management tool—such as deploying to 10% of machines per day—to catch any late-breaking issues.

For organizations using Windows Autopatch, the service already introduces optional updates to test rings automatically, but you can override its schedule to give the canary ring extra evaluation time.

Remediation playbook: when things go wrong

Despite best efforts, some machines will fail KB5089573. Having a prepared remediation plan reduces downtime. Here are the most critical steps:

Dealing with 0x800f0922 (EFI partition full)

  1. Confirm the error: Check the Update History or run Get-WindowsUpdateLog to retrieve the setup log. Search for 0x800f0922.
  2. Extend the EFI partition using a WinPE bootable USB: Microsoft provides a script in the “WinPE: Create USB Bootable drive” documentation to automate this. Third-party tools like EaseUS Partition Master also work but require caution.
  3. Manually resize with diskpart: If you’re comfortable with command-line tools:
    - diskpart
    - list disk
    - select disk 0 (adjust to the OS disk)
    - list partition
    - Identify the EFI partition (type: System, typically 100MB)
    - select partition X
    - shrink desired=250 minimum=250 (on the adjacent partition, then extend the EFI partition)
    Note: This process varies depending on partition layout. Always have a full backup.
  • Stop and restart the Print Spooler service: Get-Service Spooler | Restart-Service
  • If the crash reoccurs, uninstall KB5089573 via wusa /uninstall /kb:5089573 and block the update until a driver workaround is available.

Audio dropouts

  • Navigate to Control Panel → Sound → Playback → select your device → Properties → Enhancements → check “Disable all enhancements.”
  • Update the audio driver from the OEM’s website; some vendors have released patches in response to this update.

The bigger picture: Windows 11’s servicing evolution

KB5089573 also signals how Windows servicing is maturing under Microsoft’s new leadership. Since the inception of Windows 11, the release health dashboard has become more transparent, and known issues are published earlier in the preview cycle. Yet, the sheer variety of hardware configurations—especially with the rise of Arm-based Copilot+ PCs—means that no single test pass can cover every edge case. Community-driven testing remains a vital layer of quality assurance.

The optional preview model, when respected with proper piloting, ultimately gives organizations more control. Admins who invest the first week in careful vetting can avoid helpdesk calls that would otherwise spike after a forced Patch Tuesday rollout. With the next mandatory security update scheduled for June 9, 2026, the insights gained from current KB5089573 pilots will directly inform whether those accumulated fixes land smoothly.

Final takeaways

  • KB5089573 is a quality preview, not a security fix. It’s entirely acceptable to skip it and wait for the June Patch Tuesday cumulative update, which will include the same improvements after further refinement.
  • Check your EFI partition size before you click “Install.” A quick diskpart check can save hours of recovery.
  • Use deployment rings religiously. Even a tiny canary ring catches the hairiest bugs.
  • Monitor the Windows release health dashboard for late-breaking known issues. Microsoft sometimes adds new entries in the days after a preview ships.

For most home users, the risks are low provided they have a recent system restore point. But for business environments, the rule remains: pilot first, deploy later. KB5089573 may eventually prove to be one of the smoother optional updates, but until the data from test rings is in, caution is the only sensible posture.