If an in-place upgrade from Windows 10 to Windows 11 fails with various error codes, the first place to look is NOT the software or a hunt for old drivers, etc. Instead — especially with Gigabyte motherboards — try updating the BIOS.
I have now had quite a few machines where the upgrade worked without making any changes to Windows, drivers, or partitions, simply because the BIOS version was updated beforehand. This applies particularly to the first generations officially supported for the upgrade: 8th- and 9th-generation Intel processors.
So: Be sure to check whether an update is available for the motherboard in use (also because of the expiring Secure Boot certificates) and install it before looking elsewhere and potentially turning the search into a very time-consuming one.
If you want to have some fun, clone your existing system into a VM using, for example, VMware Workstation Pro (which is now available for free from Broadcom). If the upgrade works there on the first try, the hardware is very likely to blame — since the hardware in the VM is, of course, entirely different.
