# X_ACTION_ERRORS_INVALID

## Means

an errors: list names a code that cannot be declared there

## Typical cause

an action or query lists a code in errors: that is not X_SCREAMING_SNAKE, has no registered 4xx status, or is listed twice

## Fix

`declare the code with defineError({ code, title, status, cause, fix }) first (a 4xx status), then list it once; x errors explain <CODE> --json`

[Core and runtime](/error-codes#core-and-runtime)