Thanks for your reply. The Safe_OS error usually happens during the early phase of the Windows 11 upgrade when Windows is checking drivers, system files, or disk configuration. This is commonly caused by incompatible drivers, third-party antivirus, disk errors, or corrupted system files.
Disconnect everything external except your keyboard and mouse. If you have any third party antivirus installed, temporarily uninstall it since it can interfere with the upgrade process. It’s also important to manually update your main drivers from your laptop or motherboard manufacturer’s website, especially the chipset, storage or SATA/NVMe, graphics, and network drivers. Avoid relying only on Device Manager because it doesn’t always provide the latest versions.
Before trying again, you can also perform a clean boot to minimize background services that might block the installation: https://support.microsoft.com/topic/how-to-perform-a-clean-boot-in-windows-da2f9573-6eec-00ad-2f8a-a97a1807f3dd
Then run system checks by opening Command Prompt as Administrator and typing sfc /scannow, and after that, DISM /Online /Cleanup-Image /RestoreHealth. Make sure you also have at least 40GB of free space on your system drive.
Once everything is done, try upgrading using the Windows 11 Installation Assistant again.