This error matches a known Windows 11 25H2 issue where the update fails because the EFI System Partition (ESP) has too little free space. On affected devices, installation can fail during restart and roll back with messages such as “Something didn’t go as planned. Undoing changes.” Microsoft states this especially affects devices with 10 MB or less free on the ESP.
Recommended path:
- Install the latest Windows update available
- Microsoft resolved this issue in updates released May 26, 2026 (KB5089573) and later.
- If that newer update is offered, install it first.
- Check the failed update error in Update history
- Go to Start > Settings > Windows Update > Update history.
- Confirm the failed update and error code.
- If the device is still trying to install an older affected update, use the Microsoft workaround
- Warning: Editing the registry incorrectly can cause system issues. Back up the registry first.
- Open Command Prompt as Administrator.
- Run:
reg add "HKLM\SYSTEM\CurrentControlSet\Control\Bfsvc" /v EspPaddingPercent /t REG_DWORD /d 0 /f - Restart the device.
- Retry Windows Update.
- Restart again to allow Known Issue Rollback to apply faster
- Microsoft notes this mitigation automatically propagates to consumer and non-managed business devices.
- If updates are still blocked, try the standard Windows Update cleanup steps
- Warning: These steps require administrator permissions and command-line changes.
- Open Command Prompt as administrator and run these commands one at a time:
net stop bits net stop wuauserv ren %systemroot%\softwaredistribution softwaredistribution.bak ren %systemroot%\system32\catroot2 catroot2.bak net start bits net start wuauserv - Restart the PC and try Windows Update again.
- Also remove common upgrade blockers before retrying
- Disconnect nonessential external hardware.
- Temporarily uninstall non-Microsoft antivirus software.
- Uninstall nonessential older software.
The large free space on the main drive does not rule this out, because this specific failure is tied to free space on the EFI System Partition, not the main Windows partition.