Can Not Upgrade my computer to Win 11

It sounds like you’ve already tried most of the key troubleshooting steps — nice work narrowing it down. The 0xC1900101 - 0x30018 error usually points to a driver conflict during installation.

Here are a few things that often fix it:

Unplug all external devices (USB drives, gaming peripherals, external SSDs).

Update or temporarily uninstall GPU drivers, especially NVIDIA ones — the installer sometimes conflicts with older drivers.

Disable antivirus or security tools before upgrading.

Free up at least 30–40 GB on your C: drive.

Try Windows 11 Installation Assistant from the Microsoft site instead of the Update tool.

If that still fails, perform a clean install using a bootable USB after backing up your data.

Many ROG laptop users fixed this exact issue by updating the BIOS from ASUS support first — definitely worth checking before giving up.