Error 0x800f0922 is one of those Windows Update errors that appears at the worst possible moment — the update is downloading, the machine restarts, progress reaches 35%, and then it rolls back with the message “Something didn’t go as planned. Undoing changes.”
Then the same update appears in your queue tomorrow. And the next day. The cycle repeats until you fix what is actually wrong.
On Windows 11, Microsoft has confirmed that multiple 2026 security updates are failing to install on some devices, resulting in error code 0x800f0922. According to the company, the failures occur during the reboot phase of the installation process, typically around 35 percent complete.
This guide explains every confirmed cause of 0x800f0922 in 2026, gives you diagnostic steps to identify which cause applies to your system, and walks through every fix in order of what to try first.
What Does 0x800f0922 Mean?
Error code 0x800f0922 is a Windows servicing error that indicates the update installation failed during a critical phase — typically the boot-level file staging that happens during system restart.
It is not one error with one cause. In 2026, 0x800f0922 has appeared for three distinct reasons, and the fix depends entirely on which cause is triggering it on your system. Applying the wrong fix wastes time. The diagnostic section below helps you identify the correct cause before trying any fix.
The error produces a CBS log entry that looks like this:
Info CBS Setting original failure status: 0x800f0922,
last forward execute state: CbsExecuteStateResolvePendingThe update rolls back completely. Windows returns to its previous state. The update reappears in Windows Update as pending. The cycle repeats on every subsequent attempt until the underlying cause is fixed.
Which 2026 Updates Triggered 0x800f0922
This error became significantly more common in 2026 because Microsoft’s security updates began requiring more space in the EFI System Partition for boot-level security files. Every major 2026 Patch Tuesday triggered it on affected systems:
Microsoft has resolved a known issue causing installation failures and 0x800f0922 errors when deploying the May 2026 Windows 11 security update KB5089549.
The confirmed affected updates include KB5074109 in January 2026, KB5079473 in March, KB5089549 and KB5085516 also in March and May, and KB5094126 in June. If you have been seeing 0x800f0922 through any of these updates, your system has the EFI partition issue that every fix in this guide addresses.
Microsoft confirmed that PCs upgraded to Windows 11 24H2 or 25H2 — especially machines upgraded from Windows 10 — may fail to install the June 2026 cumulative update with 0x800f0922. Clean installs are far less affected.
Step 1 — Diagnose Your Specific Cause First
Before attempting any fix, read your CBS log to confirm what is actually failing. This takes two minutes and tells you exactly which fix to apply.
Open File Explorer and navigate to:
C:\Windows\Logs\CBS\Open CBS.log in Notepad. Press Ctrl+F and search for the word error (with a comma and space after it: error). Focus on the first error in the log — that is the one that triggered the rollback. Subsequent errors are usually cascading failures from the first one.
If you see any of these — go to Fix 1 (EFI Partition):
The root cause was discernible by searching the CBS log for the first error. The error included HRESULT_FROM_WIN32(ERROR_DISK_FULL). The root cause was that the boot partition was nearly full — it had so little free space the updater couldn’t add some files to it, hence the disk-full error.
HRESULT_FROM_WIN32(ERROR_DISK_FULL)SpaceCheckServicingBootFiles failedERROR_DISK_FULL
If you see this — go to Fix 4 (SecureBootEncodeUEFI Task):
This issue occurs because the scheduled SecureBootEncodeUEFI task is corrupted. In the Task Scheduler event log, you see Event ID 146: Task Scheduler failed to load task “\Microsoft\Windows\PI\SecureBootEncodeUEFI” at service startup. Additional Data: Error Value: 2147942402.
If the log shows component store corruption — go to Fix 6 (DISM).
The Three Root Causes Explained
Root Cause 1 — Full EFI System Partition (Most Common in 2026)
The most common cause of the 0x800f0922 Windows 11 update error in 2026 is a full EFI System Partition. Modern security updates require space in this hidden partition, but it often gets clogged with old BIOS update files or language fonts.
The EFI System Partition — also called the System Reserved Partition or ESP — is a small hidden partition, typically 100MB, that Windows uses during the boot process. It stores bootloader files, Secure Boot certificates, and boot-time security components.
The problem occurs on devices with limited free space in the EFI System Partition. Systems with 10MB or less available space are most likely to fail.
Verify that the System Reserved Partition has at least 500 MB of free space, as a lack of capacity in this hidden partition is a frequent trigger for installation timeouts.
Over time, the ESP accumulates files that are no longer needed — old font files used during initial Windows setup, stale BIOS update packages left by manufacturer utilities, and old certificate files. These files consume space without providing any ongoing value, and eventually the partition fills up to the point where Windows Update cannot add the boot security files it needs during installation.
This issue shows how Windows 11 updates are becoming more dependent on modern hardware and storage configurations. Older computers and upgraded systems are more likely to encounter these kinds of installation problems.
Root Cause 2 — Corrupted SecureBootEncodeUEFI Task
This issue occurs because the scheduled SecureBootEncodeUEFI task is corrupted. In the Task Scheduler event log, Event ID 146 appears: Task Scheduler failed to load task “\Microsoft\Windows\PI\SecureBootEncodeUEFI” at service startup. Additional Data: Error Value: 2147942402.
This cause is more common on Windows Server environments and on systems that have had their Task Scheduler database corrupted by a previous failed update or system event.
Root Cause 3 — Disabled .NET Framework 3.5 or Corrupted Components
Other common causes include disabled .NET Frameworks or corrupted Windows Update cache folders.
Some Windows 11 updates have a dependency on .NET Framework 3.5 being enabled. If it is disabled, the update fails during component staging with 0x800f0922.
Root Cause 4 — TPM 2.0 Missing (Unsupported Hardware)
If you installed Windows 11 on an older, unsupported PC by using a tool like Rufus to bypass the TPM 2.0 and Secure Boot requirements, this might be why your update is failing. Starting in late 2025 and moving into 2026, Microsoft has begun heavily enforcing hardware checks during security updates. If your system lacks a physical TPM 2.0 chip, updates may automatically fail with error 0x800f0922.
Every Fix — In Order
Fix 1 — Clear EFI System Partition Font Files (Fastest Fix)
This resolves 0x800f0922 in the majority of 2026 cases. The font files stored in the EFI partition are only used during initial Windows setup — they serve no purpose after Windows is installed and take up significant space.
Open Command Prompt as administrator and run each command in sequence:
cmd
mountvol S: /SThis mounts the EFI System Partition as drive S:. Now navigate to the fonts folder:
cmd
del /f /s /q S:\EFI\Microsoft\Boot\Fonts\*.*Then unmount:
cmd
mountvol S: /DOpen an elevated Command Prompt, run mountvol S: /S, delete the stale fonts under S:\EFI\Microsoft\Boot\Fonts, run mountvol S: /D to unmount, then retry the update.
After completing these steps, go to Settings, Windows Update, and retry the failed update. In most cases, the update will now install successfully.
What you are deleting: Font files used by the Windows boot environment during initial OS setup. After Windows is installed, these fonts are never accessed again. Deleting them is safe and recoverable — Windows can regenerate them if ever needed.
Fix 2 — Clear Old BIOS Update Files From EFI Partition
If Fix 1 did not free enough space, BIOS update packages may also be consuming EFI space.
Mount the EFI partition:
cmd
mountvol S: /SCheck what is consuming space:
cmd
dir S:\ /sLook for subfolders not belonging to Windows — common offenders include folders named after hardware manufacturers (HP, DELL, ASUS, LENOVO) containing old BIOS update packages. These can be safely deleted.
Unmount after cleanup:
cmd
mountvol S: /DFix 3 — Enable .NET Framework 3.5
If your CBS log does not show a disk full error but .NET Framework 3.5 is disabled, this fix addresses the dependency gap.
Go to Control Panel, Programs, Turn Windows features on or off. Find .NET Framework 3.5 (includes .NET 2.0 and 3.0) in the list and check the box. Click OK and let Windows download and enable the feature. Restart and retry the update.
Alternatively via Command Prompt as administrator:
cmd
DISM /Online /Enable-Feature /FeatureName:NetFx3 /AllFix 4 — Fix the SecureBootEncodeUEFI Task
If your CBS log showed the corrupted Task Scheduler entry rather than disk full errors, this is the fix.
Open Task Scheduler — search for it in the Start menu. Navigate through the left panel to Task Scheduler Library, Microsoft, Windows, PI. Look for the SecureBootEncodeUEFI task. If it shows an error state or cannot be opened, right-click and delete it.
Then run SFC to let Windows attempt to recreate the task from its stored backup:
cmd
sfc /scannowRestart after SFC completes and retry the update.
Fix 5 — Run Windows Update Troubleshooter
Go to Settings, System, Troubleshoot, Other troubleshooters. Run Windows Update. The troubleshooter checks for stopped services, registry issues, and cache corruption. Apply any suggested fixes and restart before retrying the update.
Fix 6 — Run DISM and SFC
DISM cleanup and component reset are proven fixes for the June 2026 update failures.
Open Command Prompt as administrator:
cmd
DISM /Online /Cleanup-Image /RestoreHealthWait for completion — this can take 15 to 30 minutes. Then:
cmd
sfc /scannowRestart after both complete and retry Windows Update.
Fix 7 — Reset Windows Update Components
Open Command Prompt as administrator and run:
cmd
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 msiserver
net start bits
net start cryptSvc
net start wuauservRestart and retry Windows Update.
Fix 8 — In-Place Upgrade Repair (Last Resort)
In-place upgrade is the last resort for 0x800f0922 when all other fixes have failed.
Download the Windows 11 Installation Media tool from Microsoft’s website and run a repair upgrade. This reinstalls Windows 11 over itself — preserving all files, apps, and settings — while rebuilding the component store and clearing update blockages.
This takes 30 to 60 minutes but resolves virtually every persistent 0x800f0922 instance that other fixes could not address.
Quick Diagnostic Table
| CBS Log Entry | Root Cause | Fix to Apply |
|---|---|---|
| HRESULT_FROM_WIN32(ERROR_DISK_FULL) | EFI partition full | Fix 1 then Fix 2 |
| SpaceCheck or ServicingBootFiles failed | EFI partition full | Fix 1 then Fix 2 |
| SecureBootEncodeUEFI Task Scheduler error | Corrupted task | Fix 4 |
| No .NET 3.5 in features list | .NET disabled | Fix 3 |
| Component store corruption | Corrupted Windows files | Fix 6 |
| No specific error visible | Generic | Fix 5 then Fix 7 |
| All fixes failed | Deep corruption | Fix 8 |
Microsoft’s Response — When They Acknowledged It
Microsoft has resolved a known issue causing installation failures and 0x800f0922 errors when deploying the May 2026 Windows 11 security update KB5089549. These failures are caused by insufficient free space on the EFI System Partition, which results in the update automatically rolling back on impacted devices. Users affected by these installation problems see a “Something didn’t go as planned. Undoing changes.” message when the update rolls back, and may also find SpaceCheck and ServicingBootFiles failed log entries pointing to insufficient ESP free space.
“This issue affects devices with limited free space on the EFI System Partition, especially when the device has 10 MB or less space available,” Microsoft said.
Microsoft also provided a Registry workaround ahead of the permanent fix:
The Registry workaround should fix the problem, but Microsoft does not recommend that average users rush to edit system settings unless the update keeps failing after multiple attempts. For most people, waiting for the automatic fix is the safer option.
The permanent fix for the May 2026 instance shipped in KB5089573 — the May 26 optional preview update. The June 2026 update KB5094126 also incorporated improvements to the ESP space check. If you are encountering 0x800f0922 with the July 2026 update KB5101650, applying Fix 1 remains the most reliable resolution.
Why This Error Is More Common on Upgraded PCs
This issue shows how Windows 11 updates are becoming more dependent on modern hardware and storage configurations. Older computers and upgraded systems are more likely to encounter these kinds of installation problems.
The pattern is consistent across community reports: PCs that were upgraded from Windows 10 to Windows 11 experience this error far more frequently than clean Windows 11 installs.
The reason is the EFI partition size. When you upgrade from Windows 10, the EFI System Partition created during the original Windows installation — often in 2017 or 2018 — is the same small partition that Windows 11 now needs to use for more extensive boot security files. Over years of BIOS updates, Windows upgrades, and monthly patches, that partition accumulates files. By 2026, many upgraded systems have less than 10MB of free ESP space.
A clean Windows 11 installation creates a larger EFI partition that accommodates modern security requirements — which is why clean installs rarely see this error.
Preventing 0x800f0922 From Coming Back
After applying Fix 1 or Fix 2 to resolve the immediate error, check your EFI partition free space periodically to prevent it from filling up again.
Mount and check available space:
cmd
mountvol S: /S
dir S:\
mountvol S: /DIf the EFI partition free space drops below 50MB again, the font deletion fix should be re-applied. BIOS update tools — particularly from HP, Dell, and Lenovo — sometimes restore files to the EFI partition during system updates. Clearing them after each major BIOS update keeps the partition from filling up.
For IT administrators managing fleets of upgraded Windows 10 to Windows 11 machines, the EFI partition cleanup should be added to the pre-patching checklist before each major Patch Tuesday deployment.
Frequently Asked Questions
What is error 0x800f0922?
Error 0x800f0922 is a Windows Update installation failure code that typically appears when an update fails during the boot-phase staging process. The most common cause in 2026 is insufficient free space on the EFI System Partition. Other causes include a corrupted SecureBootEncodeUEFI task, disabled .NET Framework 3.5, and missing TPM 2.0 hardware.
Why does 0x800f0922 appear at 35%?
The failure occurs at approximately 35% during the reboot phase because that is when Windows attempts to write boot-level security files to the EFI System Partition. If the partition is full, the write fails, Windows cannot continue the installation, and it rolls back the update.
How do I fix 0x800f0922 caused by a full EFI partition?
Open Command Prompt as administrator. Run mountvol S: /S to mount the EFI partition. Run del /f /s /q S:\EFI\Microsoft\Boot\Fonts\*.* to delete unused font files. Run mountvol S: /D to unmount. Retry Windows Update. This resolves the majority of 2026 0x800f0922 cases.
Why is 0x800f0922 more common on upgraded PCs?
PCs upgraded from Windows 10 to Windows 11 have older, smaller EFI System Partitions created when Windows 10 was installed. Over years of BIOS updates, Windows upgrades, and monthly patches, these partitions accumulate files and eventually fill up. Clean Windows 11 installations create larger EFI partitions that accommodate modern security update requirements.
Which 2026 Windows updates triggered 0x800f0922?
Multiple 2026 Patch Tuesday updates triggered this error on affected systems, including KB5074109 (January), KB5079473 (March), KB5085516 (March OOB), KB5089549 (May), and KB5094126 (June). Microsoft acknowledged the issue publicly for the May 2026 update and provided a permanent fix in KB5089573.
Is 0x800f0922 dangerous — does it damage Windows?
No. When 0x800f0922 occurs, the update rolls back completely and Windows returns to its previous state. The error does not damage Windows or corrupt files. However, leaving the failed update uninstalled means missing security patches, which increases vulnerability exposure.
What is the SecureBootEncodeUEFI cause of 0x800f0922?
On some systems — particularly Windows Server environments — 0x800f0922 is caused by a corrupted SecureBootEncodeUEFI task in Task Scheduler. Event ID 146 appears in the Task Scheduler log. The fix is to delete the corrupted task and run SFC to allow Windows to recreate it.
How do I read CBS logs to diagnose 0x800f0922?
Navigate to C:\Windows\Logs\CBS\ and open CBS.log in Notepad. Press Ctrl+F and search for “error,” followed by a comma and space. Focus on the first error entry — entries showing HRESULT_FROM_WIN32(ERROR_DISK_FULL), SpaceCheck, or ServicingBootFiles failed confirm the EFI partition cause.
Related error codes
| Code | What it means | How it differs from 0x800f0922 |
|---|---|---|
| 0x80073712 | A component manifest is missing from the store | Store corruption rather than partition space — 0x800f0922 is never about a missing component |
| 0x80070070 | Not enough disk space | Names the space problem directly; 0x800f0922 hides the same cause behind a generic install-stage failure |
| 0x80070643 | Fatal error during installation | Usually .NET or the WinRE partition, not the EFI System Partition |
A full index of the codes covered on this site is at Windows error codes.
