My purpose in making this thread is to learn more about what is going on in my system, why, and if my solution is actually viable long-term, as well as helping anyone else who runs into the same issues. I'm lucky that I seem to have solved the problem but I'm still 80% in the dark about what actually happened, and I'm worried my solution isn't sustainable.
On attempting a boot from the Windows 10 SDD, I am confronted with the grub-rescue screen, with the error message "no such device: 5bff...". However, Manjaro boots up as one would expect with no noticeably abnormal behavior.
I built a brand new system about a month ago and installed Windows 10 on a new 500gb SDD. I just hooked up an old 500gb HDD and installed Manjaro on it. I simply used the Manjaro installer, selected the HDD for the install, and told it to erase the whole drive. I did this without consulting any dual-boot tutorials (not smart).
sudo parted -l:
According to my own research, the "msdos" and "ntfs" fields mean that the Windows SSD uses Legacy booting, while the "gpt" and "esp" fields mean that Manjaro HDD uses UEFI booting:
Model: ATA Samsung SSD 860 (scsi) Disk /dev/sda: 500GB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size Type File system Flags 1 1049kB 525MB 524MB primary ntfs boot 2 525MB 500GB 499GB primary ntfs 3 500GB 500GB 573MB primary ntfs msftres Model: ATA WDC WD5000AAKS-0 (scsi) Disk /dev/sdb: 500GB Sector size (logical/physical): 512B/512B Partition Table: gpt Disk Flags: Number Start End Size File system Name Flags 1 2097kB 317MB 315MB fat32 boot, esp 2 317MB 500GB 500GB ext4
/boot/efi/EFI/ contains no Microsoft directory, which makes sense because Windows doesn't use EFI.
Following this guide (archive.org link), I used a different Windows machine to create a Windows installation tool on a USB drive. Booting from this, I was able to access a command prompt. Following the guide, I executed the following commands:
bootrec /scanos bootrec /rebuildbcd bootrec /fixmbr bootrec /fixboot
However, /fixboot failed with the message "Access denied." Following the advice given here, I used diskpart to find this information:
Using the 464GB volume C:, and the volume labelled "System reset" as the argument for the /s option, I ran the following command:
bcdboot C:\windows /s S:
And received a message that said something to the effect of "Bootloader files copied successfully." It's not that I knew what this would do, it's more that I was just trying anything that seemed half-reasonable. At this point, I discovered that both my Windows and Manjaro installations could both boot successfully with no noticeable problems: on selecting my boot drive, I can choose one titled "Windows Boot Manager," whereas before the only listing was "SATA 1: Samsung 500GB SDD".
Like I said, I was lucky enough that my guesswork seems to have gotten things working again, but I'm still 80% in the dark about what's going on here. Here are the questions I still have. I will keep on researching this, feel free to throw me a bone if you have any possible insights.
- How is it possible that my Manjaro installation could have affected my Windows bootloader files on the HDD?
- Will dual booting both Legacy and UEFI systems cause problems down the line?
- Will I need to reinstall either OS?
- What would it take to convert my Windows system to UEFI?
Apologies in advance for any forum etiquette that I ignorantly violated, as I'm not on these forums much. Also a well-deserved "thank you" to @gohlip for the dozens of helpful posts he has made about similar problems.