The two categories of schema harm
Not all schema errors are equal. There are two distinct categories: implementation errors (technically incorrect JSON-LD) and semantic errors (technically valid but inaccurate or misleading claims).
Implementation errors
Implementation errors occur when your JSON-LD syntax is incorrect, a required property is missing, or a field value does not match the expected format. Examples:
- Missing required fields (an Organization without a `name` property)
- Invalid URL format in a `url` field
- Incorrect `@type` declaration (using "Business" instead of "LocalBusiness")
- Unclosed JSON brackets or missing commas
These errors cause the schema to be ignored entirely. The page looks normal to visitors, the schema tag appears in the HTML, but the engine cannot process the structured data. You lose all the citation-confidence benefits of schema without any visible indication that something is wrong.
Detection: Run the Schema.org Validator (validator.schema.org) and Google's Rich Results Test after every schema implementation or update. Both tools show errors and warnings — zero of each is the target.
Semantic errors
Semantic errors occur when your schema is technically valid but makes claims that are inaccurate or misleading. Examples:
- Claiming ratings or awards you have not received
- Declaring a service category you do not offer
- Using `AggregateRating` with fabricated review counts
- Marking a service description page as a `Product` type
Google's quality rater guidelines and AI engine trust systems specifically watch for schema that does not match page content. Pages where schema claims conflict with visible content are treated as lower-trustworthiness signals — the opposite of the benefit schema is meant to provide.
The validation habit
Make schema validation a standard part of your content workflow. Any time you update your About page, add a new article, or change your schema declarations:
- Run validator.schema.org on the updated page
- Run the Google Rich Results Test
- Confirm zero errors and zero warnings before considering the task complete
