The ls command failing with error 15 is normal since you seemingly are in a condition where you have no root established or you establish it to the “wrong” partition. Try running the commands in the screenshot I posted on the mentioned thread: find /boot/BCD
BOOTMGR missing: how to fix it? As for the problems due to which you might find BOOTMGR missing error in Windows 7/8/10/11, we offer a number of solution tips to help you. You can try them one by one until you get an error message and successfully boot the system. Solution 2 – Check the first boot device Solution 3 – Update the BIOS version Repair boot sector
Chainloader +1 or ntldr /bootmgr can be used to boot windows better. What you have done is optimize the VBR of the main section; You can repair this by running these commands in the Windows cmd repair process while booting from the installation CD:
What does chainloader + 1 tell Grub to read?
Chainloader +1 also tells GRUB to read the boot process from the first block in the partition; from a native UEFI boot, there is simply no such thing. To boot Windows in mode mode, uefi must point the installed root set to the EFI system partition containing the Windows boot loader, and the chainloader line must become chainloader /EFI/Microsoft/Boot/bootmgfw.efi .
What does Chainloader +1 mean?
So +1 actually means: lock the list at offset 2 of length 1 on the GRUB support device. It simply means that the main block, i.e. the MBR, is associated with the root device. However, in our case, the BIOS loads GRUB, which in turn loads the code into the MBR, thus forming a chain. For this reason, it is commonly referred to as a chain loader.
What is Chainloader +1?
Download the bootloader with get chainloader (see chainloader): chainloader grub > +1. `+1′ tells GRUB to read one sector from each starting point of our partition. The final description of the syntax is in the Block Elements Syntax.
What is Chainloader GRUB?
This simple method starts with a block, i.e. the MBR of the root device. The normal code in the MBR comes directly from the BIOS. However, in some cases the BIOS will load What Grub to in turn load code into the MBR, forming a chain. That’s probably why it’s called a track loader.
What is a Chainloader?
Chain loading also occurs when the loader loads the loaders added during the begin-snow process.
What is Chainloader grub?
It simply means the immediate block, which is the MBR in the root device. Usually MBR codes are loaded directly from the BIOS. However, in this case, the BIOS loads GRUB, which in turn loads a lot of code into the mbr, creating a chain. For this reason, it is literally called a track loader.

Ermias is a tech writer with a passion for helping people solve Windows problems. He loves to write and share his knowledge with others in the hope that they can benefit from it. He’s been writing about technology and software since he was in college, and has been an avid Microsoft fan ever since he first used Windows 95.