[SOLVED] Windows 11 (UEFI) and Windows 7(CSM) dual boot causes BSOD on Windows 7 every time Windows 11 runs

[Denver]

I have Windows 11 (UEFI mode) installed on an NVMe SSD (formatted as a GPT disk) and Windows 7(CSM mode) installed on a SATA SSD (formatted as an MBR Disk).

Every time I run Windows 11 and restart and switch to Windows 7, it first keeps requesting to check the disks, and then when booting it suddenly gives a BSOD and I cannot start up Windows 7. I tried all things like Safe Mode, Start Up repair using the installation disk, Easy Recovery Essentials software, etc. but it just doesn't work. I've had to reinstall Windows 7 multiple times.

Now I avoid booting into Windows 11 to avoid this issue. I want to use both the OSes. How can I get around this issue?

 

[x BlueRobot]

It seems that you're probably not changing the boot mode of your BIOS when you switch between the two operating systems. You'll need to disable Secure Boot from your BIOS before you attempt to boot up Windows 7. Windows will expect the newer boot loader when the BIOS is set to UEFI.

 

[Denver]

I've turned off secure boot actually. I've installed a version of windows 11 that works without secure boot.

 

[x BlueRobot]

Have you changed the BIOS mode prior attempting to boot into Windows 7?

 

[Denver]

I've kept the boot mode as UEFI and Legacy OpRom. That supports both.

I recently got infected with ransomware and after sorting it out by deleting all possible files and reinstalling the operating system I booted into Windows 11 and used EasyBCD to clear the original EFI boot partition (350MB) which also got encrypted. I recreated the bcd store files using EasyBCD itself. It seemed to have created both "EFI" and "boot\bcd" folders on the EFI partition.

Now I boot into Windows 7 and Windows 11 without any issues. I'm not sure if what I did fixed it but it's working now