Please help /dev/md0 Corrupted superblock

Hi all, I have little raid5 mdadm; today restarting the os I get no mount of /dev/md0, and when I try e2fsck i get:
fsck from util-linux 2.34
e2fsck 1.45.5 (07-Jan-2020)
fsck.ext4: Invalid argument while trying to open /dev/md0

The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem.  If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>
 or
    e2fsck -b 32768 <device>

if I try with differente superblock suggested (8193 and 32768) nothing change.

Please help me if you can, cause I've never had this problem since more than a year and I've some important data on the raid partition

from webmin I obtain that raid level isn't more raid5 but raid0...and md0 result inactive...if I try to mount it with sudo mount dev/md0 /home/franck/pool1 I get mount: /home/davicom/Pool1: can't read superblock on /dev/md0. what can I do?

i think the problem is that I've added a disk, and It it's viewed as /dev/sdg obviously not part of raid, and the /dev/sdj instead is part of raid

can I assign /dev-number ? to try if assigning past dev number the raid works again?

Show us an output of dmesg, if you could. That might reveal why the kernel is acting up (or your disks, potentially).

Hi and thanks for you support: I had to recreate raid5 from md0 now is md1, its now in recovery at 13%. Webmin informs me now that raid5 (now it see correct raid5 and size) is clean, degradeted and recoverying, cause a disk failed. I really hope ending recovery, ext4 fs inside is workable and intact, and I can mount it. Do you have some opinions about it? Or tips when recovery ended?

@gordon do you think it will work or can I already reckon I have lost my data?

I can't guarantee anything, but I strongly believe the recovery will work if only one drive failed.

Here's a tip: If the disk which failed is still relatively new, you might be able to return it to the manufacturer for a repair or replacement. If you can, do so. But if you can't, perhaps because the drive is too old, then maybe it's time to replace all the disks in your array. I've heard of instances where a second disk fails shortly after the first, and then you may be up the river because you may not even have inserted a new disk into the array yet (to take the place of the old, failed disk).

How old are these disks? Are they different ages? Is the one that failed different in any way from all the others (manufacturer, model number, age)? Or, do you not know which disk failed?

thanks for your support but I almost lost hope, I know that there is nothing left of the ext4 fs that was inside, or at least I don't know how to withdraw it, a big loss:

root@server:~# e2fsck /dev/md/server:1
e2fsck 1.45.5 (07-Jan-2020)
ext2fs_open2: Bad magic number in super-block
e2fsck: Superblock invalid, trying backup blocks...
e2fsck: Bad magic number in super-block while trying to open /dev/md/server:1

The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem.  If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>
 or
    e2fsck -b 32768 <device>

root@server:~# dumpe2fs /dev/md/server:1 | grep superblock
dumpe2fs 1.45.5 (07-Jan-2020)
dumpe2fs: Bad magic number in super-block while trying to open /dev/md/server:1
Couldn't find valid filesystem superblock.

root@server:~# mke2fs -n /dev/md/server:1
mke2fs 1.45.5 (07-Jan-2020)
mke2fs: Size of device (0x2ba9dd800 blocks) /dev/md/server:1 too big to be expressed
	in 32 bits using a blocksize of 4096.

At this point I can't determine exactly what your system setup is, so I'd strongly suggest professional help. No, not a psychiatrist, a data recovery professional. Either that, or do a little more searching around the 'Net for someone who has had a similar problem. Sorry, it pains me to say that unless you provide me with more info, I just can't help you.