“Bad magic number in super-block” after a dd of Mobian (Debian) image

# General overview I try to install the [Mobian](https://mobian-project.org/) OS on my Pinephone thought the [dd’s method](https://wiki.debian.org/InstallingDebianOn/PINE64/PinePhone#Method_3:_dd) as described in the official Debian documentation. Basically, I have to make a dd from an image to a partition in the SD card. # The problem But at each try, the partition is corrupted and unusable. # The process ### What I did As I said, I just follow the dd’s method of the documentation. So : 1. I formatted a partition located in /dev/sdb1 in my SD card with:

# mkfs.ext4 -F -O 64bit -L 'system' '/dev/sdb1'
mke2fs 1.47.0 (5-Feb-2023)
/dev/sdb1 contains a ext4 file system labelled 'system'
        last mounted on Wed Jun 25 18:44:21 2025
Creating filesystem with 28703488 4k blocks and 7176192 inodes
Filesystem UUID: e7df3b8b-a2fa-4cce-a833-5fd86456cad8
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,
        4096000, 7962624, 11239424, 20480000, 23887872

Allocating group tables: done
Writing inode tables: done
Creating journal (131072 blocks): done
Writing superblocks and filesystem accounting information: done

2. Then, I get the image and unpack it:

$ wget https://images.mobian.org/pinephone/mobian-pinephone-phosh-12.0.img.gz 
$ unp mobian-pinephone-phosh-12.0.img.gz

3. So, I copied the image to the partition /dev/sdb1:

# dd bs=64k if=mobian-pinephone-phosh-12.0.img of=/dev/sdb1 status=progress 
5989138432 octets (6,0 GB, 5,6 GiB) copiés, 265 s, 22,6 MB/s
91552+1 enregistrements lus
91552+1 enregistrements écrits
6000000000 octets (6,0 GB, 5,6 GiB) copiés, 265,823 s, 22,6 MB/s

### What I got At this point, when the process reach it end, the partition appear as defective. 1. I check /dev/sdb1 with fsk.ext4 :

# fsck.ext4 /dev/sdb1
e2fsck 1.47.0 (5-Feb-2023)
ext2fs_open2: Bad magic number in super-block
fsck.ext4: Superblock invalid, trying backup blocks...
fsck.ext4: Bad magic number in super-block while trying to open /dev/sdb1

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 
 or
    e2fsck -b 32768 

Found a gpt partition table in /dev/sdb1

2. I inspected what happened with dmesg but found nothing special:

# dmesg -T
[mer. 25 juin 18:44:02 2025] sd 3:0:0:0: [sdb] 244285440 512-byte logical blocks: (125 GB/116 GiB)
[mer. 25 juin 18:44:02 2025] sd 3:0:0:0: [sdb] Write Protect is off
[mer. 25 juin 18:44:02 2025] sd 3:0:0:0: [sdb] Mode Sense: 03 00 00 00
[mer. 25 juin 18:44:02 2025] sd 3:0:0:0: [sdb] No Caching mode page found
[mer. 25 juin 18:44:02 2025] sd 3:0:0:0: [sdb] Assuming drive cache: write through
[mer. 25 juin 18:44:02 2025]  sdb: sdb1
[mer. 25 juin 18:44:02 2025] sd 3:0:0:0: [sdb] Attached SCSI removable disk
[mer. 25 juin 18:44:02 2025] EXT4-fs (sdb1): recovery complete
[mer. 25 juin 18:44:02 2025] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Quota mode: none.
[mer. 25 juin 18:44:18 2025] EXT4-fs (sdb1): unmounting filesystem.
[mer. 25 juin 18:44:18 2025]  sdb: sdb1
[mer. 25 juin 18:44:18 2025] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Quota mode: none.
[mer. 25 juin 18:44:43 2025] EXT4-fs (sdb1): unmounting filesystem.

However, I tried the same process from another computer and get something more verbose with dmesg (in the this case mmcblk0 is the relevant partition):

[mar. juin 24 20:11:57 2025]  mmcblk0: p1 
[mar. juin 24 20:11:57 2025]  mmcblk0: p1 
[mar. juin 24 20:11:57 2025]  mmcblk0: p1 
[mar. juin 24 20:11:58 2025]  mmcblk0: p1 
[mar. juin 24 20:13:31 2025] mmc0: card 0001 removed
[mar. juin 24 20:13:33 2025] mmc0: cannot verify signal voltage switch
[mar. juin 24 20:13:33 2025] mmc0: new ultra high speed SDR104 SDXC card at address 0001
[mar. juin 24 20:13:33 2025] mmcblk0: mmc0:0001 SD128 116 GiB 
[mar. juin 24 20:13:33 2025]  mmcblk0: p1 
[mar. juin 24 20:13:38 2025] audit: type=1400 audit(1750788819.286:29): apparmor="DENIED" operation="open" profile="/usr/bin/evince-thumbnailer" name="/tmp/tumbler-X31LB82.png" pid=13008 comm="evince-thumbnai" requested_mask="wc" denied_mask="wc" fsuid=1000 ouid=1000
[mar. juin 24 20:13:39 2025] audit: type=1400 audit(1750788819.666:30): apparmor="DENIED" operation="open" profile="/usr/bin/evince-thumbnailer" name="/tmp/tumbler-XD3SP82.png" pid=13013 comm="evince-thumbnai" requested_mask="wc" denied_mask="wc" fsuid=1000 ouid=1000
[mar. juin 24 20:15:29 2025] EXT4-fs (mmcblk0p5): mounted filesystem with ordered data mode. Quota mode: none.
[mar. juin 24 20:16:22 2025] JBD2: Spotted dirty metadata buffer (dev = mmcblk0p5, blocknr = 1). There's a risk of filesystem corruption in case of system crash.
[mar. juin 24 20:16:26 2025] EXT4-fs error (device mmcblk0p5): ext4_map_blocks:607: inode #8: block 15237146: comm jbd2/mmcblk0p5-: lblock 26 mapped to illegal pblock 15237146 (length 1)
[mar. juin 24 20:16:26 2025] jbd2_journal_bmap: journal block not found at offset 26 on mmcblk0p5-8
[mar. juin 24 20:16:26 2025] Aborting journal on device mmcblk0p5-8.
[mar. juin 24 20:16:26 2025] EXT4-fs error (device mmcblk0p5): ext4_journal_check_start:83: comm ext4lazyinit: Detected aborted journal
[mar. juin 24 20:16:27 2025] EXT4-fs (mmcblk0p5): Remounting filesystem read-only
[mar. juin 24 20:23:19 2025] EXT4-fs (mmcblk0p5): unmounting filesystem.
[mar. juin 24 20:23:42 2025]  mmcblk0: p1 
[mar. juin 24 20:23:42 2025]  mmcblk0: p1 
[mar. juin 24 20:23:42 2025]  mmcblk0: p1 
[mar. juin 24 20:23:43 2025]  mmcblk0:
[mar. juin 24 20:23:43 2025]  mmcblk0:
[mar. juin 24 20:23:43 2025]  mmcblk0: p1
[mar. juin 24 20:23:43 2025]  mmcblk0: p1

# The question Obviously, I just ask what happened, why it doesn’t work? And how to fix it and install Mobian on this SD card?