Array Uniqueness Violation
Q-1-19 — Array Uniqueness Violation
An array contains duplicate items where the schema requires every item to be unique.
What this means
Schemas can mark an array as requiring distinct items — no value may appear twice. When your YAML lists the same value more than once in such an array, this error fires.
Why this happens
The pattern usually appears in lists of identifiers where the same
identifier appears more than once: an author listed twice in a
document’s author field, a CSS class included redundantly in a
chunk’s classes, or a tag duplicated in a post’s categories.
In configurations assembled by hand from several sources (one example pulled from documentation, another adapted from a template), the duplicate is often unintentional.
How to fix
Remove the duplicate. If the duplicates have slightly different spellings or capitalizations and you want both to appear, decide which form is canonical and unify the entries — the schema treats them as identical only when they match exactly, so a typo can hide the duplication.