Windows 11 BCD (boot configuration data) gives your PC instructions on how to boot up the operating system quickly and secure. Obviously, if the BCD is corrupted or is missing, your PC will not know what to do.
Instead, your Windows 11 PC might get stuck at the login screen, or you might get a BSOD that looks like this. 
I ran into this error while installing my motherboard and graphics drivers on my PC. I though I tried everything,
After wINDOWS bOOT mANAGER: Windows Boot Manager (What it is and why it matters) – OnMSFT.com
WHAT IS EFI/BIOS What is UEFI (and how it differs from BIOS) – OnMSFT.com
