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Unknown Property

yaml
A YAML object has a property the schema does not recognize.

Q-1-18 — Unknown Property

A YAML object has a property the schema does not recognize.

What this means

Some schemas restrict which properties an object may have, in addition to which are required (Q-1-10). Schemas of this kind are called closed: any property name outside the known set is an error. This is in contrast to open schemas, which silently accept extra properties.

When you place a property name a closed schema does not know, this error fires. The terminal message names the unknown property and the object path where it appeared.

Why this happens

The most common causes:

  • A typo. What you intended as a recognized property name landed under a misspelling. The schema does not see the intended property, and the typo looks like an unknown property.
  • A renamed property. Quarto sometimes renames properties between versions. A configuration that worked in an older version may contain a name the current schema no longer accepts.
  • A property that belongs to a different block. Nesting a key under the wrong parent in _quarto.yml (for example, a format-specific key directly under project:).

How to fix

Check the spelling of the property name first; YAML keys are case-sensitive. If the spelling is right, consult the documentation for the configuration block — the property may have been renamed, or it may belong in a sibling block.

If the property is genuinely needed and the schema rejects it, the schema may be wrong for your case; raise it as an issue with the Quarto project, naming the property and the block where you wanted to set it.