Windows 11 KB5089573 Fix for 0x800f0922 EFI Install Rollback

What is KB5089573?

KB5089573 is the out-of-band resolution patch Microsoft released on May 26, 2026 to address the 0x800f0922 install rollback that plagued the original KB5089549 cumulative update earlier in the month. The patch ships a corrected servicing stack (SSU) that writes the new bootloader payload using a streaming method, so it no longer requires the full 10 MB of contiguous free space inside the EFI System Partition that KB5089549 demanded. It also triggers a paired Known Issue Rollback (KIR) policy that disables the original failing code path on devices that already pulled KB5089549 but rolled back.

The catch: the KIR is distributed gradually via Microsoft's CDN and many home and SMB devices on consumer Windows Update channels are still waiting their turn 5–7 days after release. For those users, the manual diskpart ESP cleanup outlined below is the fastest path to a successful install — it lets KB5089573 apply right now instead of waiting for the rollback policy to reach the device.

When does it occur?

• KB5089549 already failed at 35–36% with error 0x800f0922 and rolled back
• Windows Update shows KB5089573 as "Download pending" but never starts the install
• WUSA installation of KB5089573 returns ERROR_INSTALL_FAILURE 0x80073712
• wuauclt event log shows CBS_E_INSTALLERS_FAILED after KIR claim attempts
• Dual-boot or pre-2018 image with a 100 MB EFI System Partition (ESP)
• KIR policy file Windows.Servicing.KB5089573.KIR.xml is missing from C:\Windows\System32\GroupPolicy\Machine\

Common causes

• The EFI System Partition still has less than 10 MB free, so even KB5089573's smaller payload cannot land
• The KIR policy has not been pushed to your device yet (typical delay: 3–10 days on the consumer ring)
• Group Policy is blocking the KIR XML — common on managed laptops with WSUS or Intune
• The original KB5089549 left half-written staged files in C:\Windows\SoftwareDistribution\Download\
• BitLocker is suspended in a way that confuses the boot configuration data (BCD) regeneration
• A third-party EFI bootloader (rEFInd, Clover, Ubuntu shim) is still consuming space the ESP needs
• The Windows Update agent has a corrupted wuredir.cab and cannot enumerate the new patch metadata

Step-by-step fixes

1. Confirm you actually need KB5089573. Open an elevated PowerShell window and run:

   Get-HotFix | Where-Object { $_.HotFixID -in @('KB5089549','KB5089573') }

If KB5089549 is present and current build is 26100.4751 or 26200.2310, the update already landed — no action needed. If only KB5089549 shows but winver reports 26100.4750 or lower, the rollback happened and you do need KB5089573.

1. Free space inside the EFI System Partition so the smaller payload has room. Open elevated CMD:

   diskpart
   list disk
   select disk 0
   list partition
   select partition 1
   assign letter=S
   exit

Then in the same CMD: dir S:\ → look at "bytes free". If under 10 MB, run:

   del /F /Q S:\EFI\Microsoft\Boot\Fonts\*.ttf
   del /F /Q S:\EFI\Microsoft\Boot\*.bak
   del /F /Q S:\EFI\Microsoft\Boot\BCD.LOG*
   del /F /Q S:\EFI\Microsoft\Recovery\BCD.LOG*

This usually frees 6–15 MB. Windows regenerates these files on next boot.

1. Reset Windows Update components to clear residual KB5089549 stage data:

   net stop wuauserv
   net stop cryptSvc
   net stop bits
   net stop msiserver
   ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
   ren C:\Windows\System32\catroot2 catroot2.old
   net start wuauserv
   net start cryptSvc
   net start bits
   net start msiserver

1. Force-pull the KIR policy instead of waiting for the gradual rollout. From an elevated PowerShell prompt:

   gpupdate /target:computer /force
   wuauclt /resetauthorization /detectnow
   UsoClient StartInteractiveScan

Then check C:\Windows\System32\GroupPolicy\Machine\Registry.pol was updated within the last 5 minutes (Get-Item ... | Select LastWriteTime).

1. Manually install the KB5089573 MSU if Windows Update still stalls. Download the matching package from the Microsoft Update Catalog (catalog.update.microsoft.com) — pick 2026-05 Cumulative Update for Windows 11 Version 24H2 for x64-based Systems (KB5089573) or the 25H2 variant — then run:

   wusa.exe C:\Users\<you>\Downloads\windows11.0-kb5089573-x64.msu /quiet /norestart /log:C:\kb5089573.log
   shutdown /r /t 60

1. Verify the install completed cleanly after reboot. In elevated PowerShell:

   Get-WinEvent -LogName Setup -MaxEvents 50 | Where-Object { $_.Id -in 1,2,3,4 }

Look for Event ID 2 with message "Package KB5089573 was successfully installed". winver should now show 26100.4789 (24H2) or 26200.2347 (25H2).

1. Disable third-party EFI loaders temporarily if the install still rolls back. From elevated CMD: bcdedit /enum firmware lists every UEFI boot entry. Identify entries for ubuntu, refind, clover, etc., and delete their folders from S:\EFI\ after taking a system image backup. Re-add them after KB5089573 lands.

1. Suspend BitLocker for one reboot if the device is encrypted: manage-bde -protectors -disable C: -RebootCount 1. This prevents the firmware from prompting for the 48-digit recovery key after the BCD regeneration that KB5089573 performs on first boot.

If it still doesn't work

If KB5089573 keeps failing after ESP cleanup, the underlying component store is likely corrupted. Run DISM /Online /Cleanup-Image /StartComponentCleanup /ResetBase followed by sfc /scannow. If DISM returns 0x800f081f, mount the latest Windows 11 24H2 ISO from software-download.microsoft.com and supply it as the repair source: DISM /Online /Cleanup-Image /RestoreHealth /Source:WIM:D:\sources\install.wim:1 /LimitAccess. For managed devices on WSUS, confirm the 2026-05 Servicing Stack Update for Windows 11 (KB5089569) is approved alongside KB5089573 — installing the cumulative without the matching SSU is the single most common cause of repeat rollback in enterprise environments. As a last resort, an in-place repair install using setup.exe /auto upgrade from the mounted ISO will rewrite the servicing stack while preserving apps and files.