I think it's OK.
At least, I would now know how to repair it, I hope

This is what I have in "blkid". I left out the /dev/sdx partitions.

/dev/nvme0n1p1: SEC_TYPE="msdos" UUID="5C18-CE03" TYPE="vfat" PARTLABEL="EFI System Partition" PARTUUID="9a37b632-2be9-4726-ae20-0e3ebb52cdbd"
/dev/nvme0n1p2: UUID="5dedca90-5dd5-4210-b6aa-0f2d96c6b722" TYPE="xfs" PARTUUID="08dc394d-2e1d-4b35-ad89-0768f8b6745d"
/dev/nvme0n1p3: UUID="b719d753-6db1-4d69-a72e-97bfde3c1a7a" TYPE="xfs" PARTUUID="d34693a7-83a7-4a60-ba02-2d69d131fe50"
/dev/nvme0n1p4: UUID="b5035d6d-c564-4c2c-9e8b-d269c9cfd5fa" TYPE="swap" PARTUUID="09faf8f2-1cce-4db0-8e52-301201820ef6"
/dev/nvme0n1p5: UUID="okFsKQ-yTWf-CZ3J-Rbiw-2HDf-1A6k-2b7KFG" TYPE="LVM2_member" PARTUUID="d18a34a2-76de-4fe5-9452-e16b8fac05a2"
/dev/mapper/clearos-UserDisk1: LABEL="UserDisk1" UUID="7517634c-7217-43f5-8518-65fed898522d" TYPE="xfs"
/dev/mapper/clearos-UserDisk2: LABEL="UserDisk2" UUID="dedd44a1-a898-4f72-b1f4-3046bb7266f6" TYPE="xfs"
/dev/mapper/clearos-UserDisk3: LABEL="UserDisk3" UUID="38283ce5-1dd6-4b78-8ab8-449fa575824d" TYPE="xfs"
/dev/mapper/clearos-UserDisk4: LABEL="UserDisk4" UUID="d7714581-2ec5-43a3-9bf0-bcfc23a48db0" TYPE="xfs"
/dev/mapper/clearos-Razno: LABEL="Razno" UUID="8a069207-45ad-47f4-a0f7-fe725437a807" TYPE="xfs"
/dev/nvme0n1: PTTYPE="gpt"

This is what I have in /etc/fstab I also left out the /dev/sdx partitions.

UUID=b719d753-6db1-4d69-a72e-97bfde3c1a7a / xfs defaults 0 0
UUID=5dedca90-5dd5-4210-b6aa-0f2d96c6b722 /boot xfs defaults 0 0
UUID=5C18-CE03 /boot/efi vfat umask=0077,shortname=winnt 0 0
/dev/mapper/clearos-Razno /var/flexshare/shares/backup xfs defaults 0 0
/dev/mapper/clearos-UserDisk1 /var/flexshare/shares/userdisk1 xfs defaults 0 0
/dev/mapper/clearos-UserDisk2 /var/flexshare/shares/userdisk2 xfs defaults 0 0
/dev/mapper/clearos-UserDisk3 /var/flexshare/shares/userdisk3 xfs defaults 0 0
/dev/mapper/clearos-UserDisk4 /var/flexshare/shares/userdisk4 xfs defaults 0 0
UUID=b5035d6d-c564-4c2c-9e8b-d269c9cfd5fa swap swap defaults 0 0

Hehe, thank you Marvin, have a relaxing weekend you too

Thank you for clarifying Nick. If it was your fault, then everything is forgiven Just a little bit "stressful" day

I'm sorry for my late response Nick, I didn't have time before.
Yes, it would be nice, that you add this in the Rescue howto, if someone also has ClearOS on a NVMe SSD. If I may ask, why the Rescue option number 1 doesn't work on NVMe SSD? Will this be repaired, or is this not possible?
The answer to you questions is yes, I did like you described. I also used the "lsblk -f" command to see the partitions. If it makes any difference?

I must add only one thing. Not that I didn't want to do chroot, I couldn't. It gave me an error.

If you have any other question just ask. I hope that I will remember it correctly

Thank you for the edit. I did the update, so I'm hoping that now it will be OK if I reboot. I won't try it, until it is really necessary :P
I won't add the exclude for now, thank you for telling how to do this. Just one question, if I decide to add it later. I add this right after [main] ?

Woooooowww I didn't believed anymore that this would be solvable...
Thank you Nick and Marvin for all the help.

Nick I did a little different before you posted. Instead of the UUID=something I wrote this in sh-4.2#
mount -t xfs /dev/nvme0n1p3 /
mount -t xfs /dev/nvme0n1p2 /boot
mount -t vfat /dev/nvme0n1p1 /boot/efi

(if I didn't write down the filesystem (vfat or xfs) it gave me an error)

And then did grub2-mkconfig -o /boot/efi/EFI/clearos/grub.cfg
And exit.
And it booted...

Is it OK now? Or is the buggy grub still on my system? Must I do something? Erase it or something? I don't want to fear every time I reboot the PC and pray that it would boot...

OMG... almost 1 full day of messing around with this... I was messing around with FTP for more than a week, and then this...
Just one more question... HOW CAN I DISABLE GRUB UPDATE? I don't want to do this in a month or so again, when someone decides to release such a bug again...

Thanks one more time.

This is in /etc/fstab

UUID=b719d753.... /
UUID=5dedca90.... /boot
UUID=5C18-CE03 /boot/efi

When I type in the command "blkid" in bash-4.2# then nothing happens
I entered "exit" and then it gets me to sh-4.2#
If I enter the "blkid" command here, then it writes me all the UUIDs
I can see, that the first UUID is /dev/nvme0n1p3, second UUID is /dev/nvme0n1p2 and third UUID is /dev/nvme0n1p1

If I write "mount -a -v" in sh-4.2 it doesn't do anything, just goes in another line.
If I write "mount -a -v" in bach-4.2 is says:
/ : ignored

/boot is empty.
I don't get it. I should mount p1, p2 and p3 to /mnt/sysimage?
Or where must I mount them?

I did "mount -a" and didn't get any feedback, just a new line.
If I look in /etc/fstab it doesn't say where p1 and p2 are mounted it just says some UUID= and some long string for /boot
and UUID=5C18-CE03 for /boot/efi

I mounted now the p3 to /mnt/sysimage.
Then I run the chroot /mnt/sysimage and now it didn't return any error. Strange
It moved me from sh-4.2# to bash-4.2# what should I do now?
I checked, and there is nothing in the /boot directory.

nvme0n1p1 is /boot
nvme0n1p2 is /efiboot or vice versa, I forgot
nvme0n1p3 is /
nvme0n1p4 is swap
nvme0n1p5 is LMV and contains additional 5 disks - user disks which already has files on it, I don't want to loose that...

I did custom partitioning.