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There is only "System Setup" boot option in CentOS 8 Stream GRUB.
I was using Dual Boot Windows 10 and CentOS Stream 8. I don't know what is problem. This happened since I booted into Windows 10 for 42nd time. Since there is another boot option in BIOS for Windows 10 I can boot into it, but not CentOS. Only I can do from GRUB is go to System Setup or BIOS Setup. I Searched the web a lot for this, but didn't got any help, Does anybody know how to fix this problem?

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    Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Community Bot
    Commented Sep 16, 2021 at 14:19
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    Super User isn’t a forum. Your question has received downvotes because your plea for immediate help. Your question doesn’t have the required information to solve your problem. Your question will avoid downvotes when it doesn’t contain grammatical errors. Proper formatting helps, bolding random words, is going to draw downvotes.
    – Ramhound
    Commented Sep 16, 2021 at 14:29
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    Your urgency is not our urgency. Often a question can sit a couple of days or so before someone who can answer may see it. In the meantime, you need to add detail, rather than panic.
    – Tetsujin
    Commented Sep 16, 2021 at 14:32

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Since we at the forums won't see your system or know anything about it other than what you describe, you must act as our eyes and hands. If you are panicking, as your original message filled with "help! help!" suggested, then it will be hard for us to get any reliable information from you, and that makes it more difficult for us to help you.

CentOS 8 uses a new type of GRUB configuration that uses the blscfg module of GRUB. That module makes GRUB look at /boot/loader/entries/ directory to find Boot Loader Specification compliant files that would identify the kernel & initramfs files to boot: one *.conf file for each kernel version you currently have installed.

For some reason, it appears GRUB cannot access these files now. Maybe they are gone, or maybe something has changed so GRUB just cannot find the partition these files are located in.

You said you tried live boot of Ubuntu and it failed to mount the CentOS disk... but did you do that correctly? Your initial message did not exactly give us an impression that you would be at your best performing a finicky procedure correctly right now...

Is your Centos installation using LUKS or some other disk encryption, and if it is, did you do the proper steps to unlock the encryption first? (usually sudo cryptsetup with parameters depending on the encryption method used)

CentOS 8 uses a LVM-based disk layout by default. When using a live Linux setup, you might need to manually activate the LVM volume group before the individual logical volumes. Did you do that? This would have been sudo vgchange -ay or sudo lvchange -ay or sudo lvm lvchange -ay, and it might be needed either before or after unlocking any disk encryption, depending on exactly how your system was set up.

When you were trying to access the CentOS disk using Ubuntu live boot, what did you actually see? What did the partition table of the CentOS disk look like? Could you show it to us? Did it look like you remember it should be?

When trying to mount the CentOS disk, what was the error message you got? Did you use the command line, or did you just try using the GUI?

If the error message was about not finding a recognizable filesystem at all, it is likely that you just missed a required step in making the CentOS filesystem accessible.

If at all possible, please add hard facts like the output of fdisk -l, parted /dev/sda print (or whatever your CentOS disk is), and/or lsblk -o +fstype, and the exact commands/operations you did to your question. From those, the people reading your question can do their own reasoning and perhaps figure out something you cannot. If you just know one way to do something, there might still be other ways you don't currently know about, and one of those just might be better for this specific situation than what you are currently doing.

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  • There wasn't any encryption. There was not an error. no option to mount
    – Head
    Commented Sep 17, 2021 at 3:54
  • You would still have needed the LVM activation step, which any GUI tool would have been extremely unlikely to do. The GUI mounting tools are mostly designed for devices that contain just one filesystem like CDs or memory cards, and are unlikely to be capable of handling mounting of a system disk that uses LVM - mostly because the name of the LVM device that contains the filesystem to be mounted is outside the default list of allowed devices for non-root mounts.
    – telcoM
    Commented Sep 17, 2021 at 5:41

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