You are using a USB memory stick as update source. The upgrade process goes well until the device reboots into the minimal version 10 system. At this point, it tries to retrieve the data for the other partitions from the memory stick, but cannot find them.
The mount point created by automount has changed. In IGEL Linux 5, the mount point is /userhome/media/DISK_%UUID%, whereas in IGEL Linux 10, it is /userhome/media/%UUID%. Example: /userhome/media/DISK_756984F349BFBCAF (IGEL Linux 5) vs. /userhome/media/756984F349BFBCAF (IGEL Linux 10).
The upgrade process tries to use the old path for getting the required data, but the memory stick is mounted under the new path.
The following dialog is shown:
Solution 1: Set the Path to the New Mount Point
Solution 2: Create a Link to the New Mount Point
The mount point equals the UUID of the memory stick, e. g. 756984F349BFBCAF