Unknown Term
This message indicates an IRI from the schema.org domain was found, but it is not defined by the official vocabulary.
The most common cause for this is a typo due to misspelling or case-sensitivity. It can also occur when validating against an older Schema.org release which has not yet defined the term.
Examples
ERROR service/schema-org#UnknownTermThing
The object is not a known schema.org/Thing.
position: object
ERROR service/schema-org#UnknownTermProperty
The predicate is not a known schema.org/Property.
position: predicate
ERROR service/schema-org#UnknownTermDataType
The literal datatype is not a known schema.org/DataType.
position: objectLiteralDatatype
ERROR service/schema-org#UnknownTerm
The object is not a known schema.org term.
position: object