Filesystem change prohibited. Will not descend into or `filepath` is a different filesystem. Will not descend from.
Steps to resolve
This error means that the file is on a different file system than the current one.
Sometimes this can mean that the path following the ends in a symlink or a junction point would lead the backup process away from the current path, and thus may result in skipping all over the file structure, which would lead to skipping lots of data.
We do not follow such links away from the path we are currently backing up, we systematically traverse the file structure so as to not miss anything.
There is a setting to change this under Clients › Edit, but it is prudent to not cross file systems while doing a backups and to instead list them each explicitly.