Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
The engine refused to start because it could not read its own rulebook about data changes. Here is the rule in one sentence: nothing is ever overwritten. When you write to a name, the engine adds a new version with a later timestamp, and the current value is simply the newest version. That law has five parts: the rule itself, the ordering key, how to select the current one, how removal works, and how strict the ordering must be. All five are written in template.feml, on disk, not buried in code. This time the file could not be used. It was unreadable, or it did not state those five parts. Without it, the engine does not know what its own storage is supposed to do. It could fall back on a built-in default, but then there would be two sources of truth, and this design allows exactly one. So birth is refused. The message tells you the file path and the reason. Check that template.feml exists, can be read, and states all five parts. Then start the engine again.
Text from the Rush engine's error catalogue.