Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
Rush could not use this machine's device key, the secret that proves who this node is. Let's see where it lives. It is a small file, exactly thirty-two bytes, kept under your home directory, and it must be private: readable and writable by you alone. If the file lets the group or anyone else in, or it is not a regular file, rush refuses it, and it does not fix the permissions for you. Why? A key that others could have read is no longer a secret, so the safe move is to stop and let you decide. Other problems show up with their own verdict words. A wrong length. A home directory that is not set. A directory or a file that could not be written or read. Or a failure to draw random bytes when creating a new key. The first slot shows the path of the key file. For permissions, restrict the file so only you can access it. If you suspect it leaked, remove it, and let a new one be made, then tell whoever pinned the old one.
Text from the Rush engine's error catalogue.