Nowadays, we can see several users throng to Windows 11 and enjoying its unbounded handy features. In some cases, users are frustrated by some errors when installing Windows 11, such an error we are going to discuss today. Several users pointed out that while trying to upgrade from Windows 10 to Windows 11, they end up with 0x800fo955 – 0x20003 Installation Error, preventing them from migrating to the new Operating System.

As per users who experience the same error once the installation process reaches around 25-30 percent, the system restarts; then they receive an error message which states- “0x800F0955-0x20003 The installation failed in the SAFE_OS phase with and error during INSTALL_UPDATES operation”. This is not a serious error; in this article, we have listed a few solutions that you can try to get rid of the same issue. Let’s have a look.

Fix 1: Check the System Meets the Minimum Requirements:

If you encounter the 0x800fo955 – 0x20003 Installation Error, you need to check your system meets all the minimum requirements to install Windows 11. To do so, you need to download and install PC Health Check App on your system. Once downloaded, launch it and click on the Check now button to check your system health.

Fix 2: Enable TPM 2.0 and System Boot:

If you are not enabled TPM 2.0 and Secure Boot on your system, you will also receive the 0x800fo955 – 0x20003 Installation Error on the screen. Here you need to enter into the BIOS Mode and enable both TPM 2.0 and Secure Boot. To do so,

  • Firstly, press the F1, F2, F10, F12 or Delete button (based on the system Manufacturer) to enter into BIOS Mode.
  • Then select the Security tab from the top horizontal menu and select Security chip using your keyboard arrow buttons, and press Enter.
  • Now select Security Chip Type and Enable the TPM 2.0.
  • Again go back to the Security tab and select the Secure Boot from the left pane menu.
  • Then Enable the Secure Boot using your keyboard keys.
  • Once done, retry to install Windows 11 on your system.

Fix 3: Enable Developer Mode:

Before trying to install Windows 11, you need to make sure you enabled Developer Mode in your Windows 10. If the Developer Mode is disabled, then you might receive the 0x800fo955 – 0x20003 Installation Error between the installation process. To do so,

  • Firstly, press Windows + I simultaneously to launch the Settings app.
  • Inside the Settings screen, select For developers option from the left pane menu.Develper Mode
  • Then turn On the toggle beside the Developer Mode to enable it.
  • Once done, restart the system and then try to install Windows 11.

Fix 4: Start Windows Update Service:

Another trick to resolve the 0x800fo955 – 0x20003 Installation Error is restarting the Windows Update Service in the Services window. To do so,

  • Firstly, type Services in the Search box and open the first search result.
  • Then in the Services window, locate and select Windows Update service.
  • Double-click over it, and from the Properties window, set Startup type as Automatic and Service Status as Running (click on the Start button).
  • Once done, restart the system and try to install Windows 11 again.

Fix 5: Restart the System:

If you are constantly getting the 0x800fo955 – 0x20003 Installation Error, then you need to restart the system once or twice to get rid of the same issue. A simple restart will help you to erase existing errors on the system and starts the system anew.

Fix 6: Unplug External Devices:

Before the installation process, you need to disconnect all external peripherals, including the External Hard Disk, USB drive, Printer, Keyboard, Mouse and so on.

At the end of this article, we hope you resolved the 0x800fo955 – 0x20003 Installation Error and installed Windows 11 on your system. However, if you have any queries or doubts after reading this article, then please leave a comment in the below-given comment box.