Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
This message is retired, so you should never see it, but its story is worth hearing. There was a time when asking for the length of null raised a refusal, saying that the value has no length. Then the rule changed. Now the length of null is simply zero. Null counts nothing, and in rush, an empty collection is null, so it makes sense: nothing in it, length zero. Because of that, no row raises this id anymore. So why does it still sit in the catalogue? So its number is never reused. Imagine a street where a house was torn down. The city does not give that number to a new house, because old records and old conversations still point to it. A catalogue is a kind of memory, and an id should always mean one thing. If you are reading this in an old log, treat it as history. If you are asking for the length of a value and getting zero, you are seeing the new rule at work. Nothing to fix. The id stays reserved, and the story stays clear.
Text from the Rush engine's error catalogue.