Microsoft’s August 2026 security update for Windows 11, KB5121003, is reportedly causing installation failures on some HP systems. Affected users say the update downloads and installs normally until the required restart, after which the PC may get stuck at the HP logo, enter Automatic Repair, and eventually roll back the update. Some users have also reported that HP support attributed the problem to corrupted BIOS settings.
The issue has not been officially acknowledged by Microsoft as a BIOS-corruption bug. However, multiple users have reported similar installation failures, including on HP OmniBook X systems. In at least one Microsoft community report, an HP support representative reportedly recommended resetting the BIOS to its default settings, after which the pending update issue was resolved.
If KB5121003 is failing on your HP laptop, here’s what the reported problem looks like and what you can do to recover your system and protect your data.
What is the KB5121003 HP BIOS Issue?
KB5121003 is Microsoft’s August 11, 2026 cumulative security update for Windows 11 versions 24H2 and 25H2. The update includes security improvements, Secure Boot certificate-related changes, and other quality improvements. The HP problem appears to occur during the restart required to complete the update. According to reports, the sequence looks like this:
KB5121003 downloads > Windows restarts > HP logo appears > system fails to boot > Automatic Repair starts > Windows rolls back the update
One Microsoft community user reported experiencing the problem on an HP OmniBook X 14. After the update failed, the system returned to Windows and displayed error 0x800f0845. The same user later reported that HP support instructed them to load the default BIOS settings, after which a subsequent update installed successfully.
Neowin reported that several users had encountered similar failures and that one user said HP support identified corrupted BIOS settings as the cause. However, this remains a user-reported diagnosis. Microsoft has not listed BIOS corruption as a known issue for KB5121003 in its official Windows 11 release-health documentation.
Which HP Systems Are Affected?
There is currently no confirmed list of affected HP models. Reports include HP OmniBook X systems, including an OmniBook X 14 and an OmniBook X Flip. One Microsoft community thread also contains reports from users with other HP hardware. This suggests the problem may not be limited to a single model, but the available reports aren’t enough to establish the full scope. Therefore, avoid assuming that every HP laptop will experience the problem.
Symptoms of the KB5121003 Installation Failure
The reported symptoms can vary, but affected users may notice:
- KB5121003 downloads and begins installing normally. Then Windows asks you to restart the computer.
- The system gets stuck at the HP logo after restarting. Windows enters Automatic Repair and eventually rolls back the update.
- Windows starts normally after the rollback, and KB5121003 continues to appear as a pending update.
- Error 0x800f0845 may appear after the failed installation. Reinstalling the update manually may reproduce the same failure.
How to Fix Windows 11 KB5121003 Installation Failure on HP?
Try the following fixes in order. If your computer is still booting into Windows, start with the first method. If it cannot boot normally, move to the Windows Recovery Environment methods.
1. Let Windows Complete Automatic Repair
If your HP laptop is stuck after installing KB5121003, don’t immediately assume that the system is permanently damaged. If Windows enters Preparing Automatic Repair, Diagnosing your PC, or Attempting repairs, allow the process to complete. In reported cases, Windows eventually reversed the failed update and returned the system to its previous working state.
Once Windows starts normally:
- Sign in to Windows.
- Check Settings > Windows Update > Update history.
- Confirm whether KB5121003 failed or was rolled back.
- Do not immediately retry the installation.
- Back up important files before attempting additional troubleshooting.
If Windows remains stuck at the HP logo for an unusually long time and doesn’t enter recovery automatically, boot into Windows Recovery Environment (WinRE).
2. Load the Default BIOS Settings
Some affected HP users have reported that restoring BIOS defaults resolved the KB5121003 installation problem. The exact steps and key combinations vary by HP model, but the general process is:
- Shut down the HP computer.
- Turn it on and repeatedly press F10 until BIOS setup interface appears.
- Press F9 to load the BIOS settings. This will reset BIOS settings to their defaults.
- Press F10 to choose save and exit.
- Apply the default settings.
- Save the changes and exit BIOS.
- Allow Windows to start.
Important: BIOS settings vary between HP models. If you’ve made custom BIOS changes for storage, virtualization, Secure Boot, or other hardware settings, note them before restoring defaults so you can reconfigure them later, if necessary.
If you’re unsure which settings to change, consult the support documentation for your exact HP model rather than changing individual BIOS options at random.
3. Uninstall KB5121003
If Windows is working after the failed installation, you can check whether the update is installed and remove it, if necessary.
- Open Settings and click Update & Security.
- Go to Windows Update > Update History.
- Click Uninstall updates.
- Locate KB5121003 and remove it.
Note: If KB5121003 has already been rolled back automatically, it may not appear in the installed-update list.
4. Install the Latest HP BIOS Update for Your Model
If HP has released a newer BIOS for your specific laptop, check the manufacturer’s support page before attempting the update. This is particularly relevant because Neowin reported that HP had released BIOS version F.07 Rev.A (sp 174502.exe), whose release notes mention improving system stability when Windows Update is run.
However, don’t install a BIOS update intended for another HP model. A BIOS update is a firmware-level operation. Make sure:
- The BIOS package matches your exact HP model.
- The laptop is connected to AC power.
- The battery has sufficient charge.
- You follow HP’s installation instructions.
- You don’t interrupt the BIOS update once it begins.
If your system is already experiencing serious boot or firmware problems, consider contacting HP support before attempting a BIOS flash.
5. Try System Restore
If System Restore was enabled before the update was installed, you may be able to return Windows to an earlier restore point when it was working fine.
- Press Win + S to launch search and open Create a restore point.
- A System Properties dialog box will appear.
- Under the System Protection tab, click System Restore.
- Choose a restore point created before KB5121003 was installed and follow the instructions.
- Confirm the restore point by clicking Finish and you’re good to go. Your PC will restart to apply the changes.
What to Do If Windows Won’t Boot after KB5121003?
If your HP laptop remains stuck at the logo after a failed KB5121003 installation, focus first on getting the system back into a bootable state without putting your data at unnecessary risk.
- Allow Automatic Repair to complete.
- Enter WinRE if Windows doesn’t start.
- Use Uninstall Updates to remove the latest quality update.
- Try System Restore if an appropriate restore point exists.
- Check and restore default BIOS settings.
- Consult HP for model-specific BIOS or firmware updates.
Bottom Line
Boot loops, forced shutdowns, and repeated Automatic Repair cycles can interrupt file writes. Some users say HP support advised backing up and factory resetting the laptop. If Windows won’t start and a reset or clean reinstall is next, recover your files first. Read our guide recovering data from a non-booting Windows PC for the detailed, step-by-step procedure.
