Hi,

I had a drive with the following settings:

lsblk --output NAME,KNAME,FSTYPE,LABEL,UUID,SIZE
NAME   KNAME FSTYPE LABEL                  UUID                                   SIZE
sda    sda   udf    UDF-Externe-Festplatte 589edd3fLinuxUDF                     931,5G
├─sda1 sda1  ntfs   NTFS1000MB             6D1B61A41DAB9E71                      1000M
└─sda2 sda2  ext4   Linux-Externe-FP       c8442952-f42a-4e91-baf6-6957e30e345c 930,5G

In Dolphin it got mounted the wrong way: by clicking and mounting /dev/sda2, the corresponding mount command used instead the parent device information (i.e udf not ext4) an caused an error:

Error mounting /dev/sda2 at /run/media/andreas/UDF-Externe-Festplatte: Command-line `mount -t "udf" -o "uhelper=udisks2,nodev,nosuid,uid=0,gid=0,iocharset=utf8" "/dev/sda2"  "/run/media/andreas/UDF-Externe-Festplatte"' exited with non-zero exit  status 32: mount: wrong system filetype […]

The mount command (whatever put this together) should use the *actual* partition information and not the parent one. 

Trying « mount /dev/sda2 /run/media » works just fine, but the compositing of the command above needs to be revisited, I guess somewhere in the udev framework.

On https://forums.opensuse.org/showthread.php/526602-automount-USB-external-drive-Error-mounting-dev-sda2-(wrong-filtype-udf-vs-ext4)-udev-problem we fixed it by backup data, erasing the drive with command 

dd if=/dev/zero of=/dev/sda  bs=4096 count=8

… and partitioned it anew with gparted (previously it had some UDF history that got not erased but now its properly set due to the dd step).