I've spent a goodly amount of time trying to research out a solution to this frustrating problem that didn't use to exist. I used to be able to routinely modify the partitions, image, and format micro SD cards on my Kubuntu 16.04 box, but I can't do it any more. When I insert a micro SD card, it automatically mounts, per the system settings to perform automount upon detection. What I would usually do is unmount the micro SD card (or card partitions if there were more than one mounted) and then perform a dd command, mkfs, or use Etcher, as needed. Things just worked.

Now, when I insert a micro SD card, it auto mounts, and I can see the information on the micro SD card partitions, but unmounting it causes it to disappear entirely. I changed the system settings so as to NOT automount on detection, but the problem persists. Every micro SD card, even new, unused ones, cannot be gparted'ed, formatted, dd'ed, or etcher'ed. I have tried multiple micro SD card adapters and made absolutely sure that they were not set to read-only mode. Also, I attempted to modify existing files on micro SD carda and they could not be modified, even though they are marked are writable and the directories they are in are writable.

Any help would be appreciated.

Regards,

Mac

Have you tried booting into another kernel? Just in case your problem was a kernel change.

What do you mean by "disappear entirely"?

What do you mean by "cannot be gparted, ...."? What happens when you try, and what do you try?

In other words, to get help, tell us what exactly you do, and what are the precise failure symptoms?

Thanks for the reply.

I have not tried booting into another kernel. I will have to see if there is another kernel that I can boot into.

What I mean is that when I insert a micro SD card, it automounts, I perform 'lsblk -p' and get the following:

:~$ lsblk -p
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
/dev/sda 8:0 0 931.5G 0 disk
├─/dev/sda1 8:1 0 900.6G 0 part /
└─/dev/sda5 8:5 0 30.9G 0 part [SWAP]
/dev/sdb 8:16 1 14.5G 1 disk
├─/dev/sdb1 8:17 1 33M 1 part /media/mcody/BOOT
└─/dev/sdb2 8:18 1 14.5G 1 part /media/mcody/ROOT
/dev/sr0 11:0 1 1024M 0 rom

The SD card in on /dev/sdb. When I unmount the SD card (either by using Dolphin file manager or the umount commmand, the micro SD card 'disappears' entirely.

:~$ lsblk -p
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
/dev/sda 8:0 0 931.5G 0 disk
├─/dev/sda1 8:1 0 900.6G 0 part /
└─/dev/sda5 8:5 0 30.9G 0 part [SWAP]
/dev/sr0 11:0 1 1024M 0 rom

In the past, I was still able to 'dd' or 'etcher' the micro SD card after unmounting it. Now it is either not found, in this sitution, or not permitted, if it is still mounted. As I mentioned before, all micro SD cards appear to be write protected, even after switching adapters (micro SD to SD adapter).

Okay. I run 'sudo gparted'. I select the micro SD card (/dev/sdb). I delete the partition or partitions, depending upon what is there. I create my new partition (primary partition, use the entire free space, fat32 format, label of 'MSDOS' . I attempt to write the new partition by clicking on the green check mark. After affirming the command, the partition write starts and get the following message: 'Operation not permitted during write on /dev/sdb'. After closing the error message, gparted refreshes and displays the original partition configuration on the micro SD card. I have tried this with several micro SD cards and adapters with the same result.

Does this help?

Thanks!

Regarding the disappearance of sdb, I would look into the last few lines of the system log (commands dmesg for kernel and driver messages, or journalctl, or file /var/log/syslog).

Regarding the permission problem: I would try the parted or fdisk commands instead. I would also check if the software has declared the card to be read-only, for example by looking into /sys/class/block/sdb/ro (not sure though if the RO flag is in precisely this file on Ubuntu 16), or again the logs as above right after inserting the card.

Thanks for the suggestions. I decided to try a system reboot and that appears to have solved the problem! The micro SD cards now mount with rw permissions and gparted and Etcher now work properly. I have absolutely no clue as to what caused the problem in the first place. My workstation appeared to function properly except for the micro SD card issue.

Thanks, again, for your help and apologies for wasting your time.

Mac