Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
Your holder has a location, but the location is not one rush can accept. Let's see how locations work. If you name a filesystem with which, such as ext4, you must also give a path, and that path must be absolute, starting from the root, not relative to wherever you happen to be. If you give no which at all, your path is a leaf path, living below the leafs mount, and it must not be empty. And in both cases, rush forbids the double dot, the step that climbs out of the folder. Why so strict? Because the path is where your data lives, and a path that can wander upward could write into places you never meant to touch. So rush checks all of this first, before it opens a single file, and tells you which holder is at fault. Imagine you wrote which ext4 but forgot the path, or wrote a path like dot dot slash data. Both are refused. The second slot of the message shows the spelling that would be accepted. Copy that shape, fix your holder, and run again. Nothing was touched, so there is nothing to clean up.
Text from the Rush engine's error catalogue.