After an upgrade, you might see an entry for "Windows 7" or "Windows Old" in your boot menu. To remove it:
bcdedit /export C:\BCD_Backup
bcdedit /debug current on
When Windows fails to boot, BCDEdit (via recovery console) is often the only way to rebuild the bootloader, disable unsigned driver checks, or turn off automatic reboot on BSOD.
If you dual-boot, you might want more time to select your OS. To set the menu timeout to 30 seconds: bcdedit /timeout 30 Use code with caution. C. Disabling/Enabling Automatic Repair