Structured Data Testing: How to Debug Schema Errors in Google's Tools

The Tools Are Not Infallible

From my experience perfectly valid JSON-LD pass the Rich Results Test and then fail to produce rich results for weeks. Why? Because the testing tool validates syntax, not context.

Here's how to actually debug schema.

Step 1: Start With Schema.org's Validator

Before you touch Google's tools, paste your JSON-LD into the Schema.org validator. It catches structural issues Google's tools miss. Specifically: missing @type hierarchies, incorrect property nesting, and enum mismatches.

Last month I found a client using @type: "Product" with brand as a string instead of brand: { @type: "Brand", name: "..." }. The Rich Results Test passed. Schema.org's validator flagged it immediately.

Step 2: The Rich Results Test Is for Preview, Not Validation

Google's own docs say this tool "shows which rich results can be generated." Note the word "can." It doesn't mean they will.

The gotcha: If your page passes the Rich Results Test but you don't see rich results in Search Console's Performance report after two weeks, check:

• Is the page actually indexed? (use the URL Inspection Tool)
• Does the page need dateModified for Article schema? (85% of skipped Article rich results we've debugged lack a date)
• Is the page competing with another rich result type? (breadcrumb + product can conflict)

Step 3: Search Console's Rich Results Report

This is your source of truth. The error messages are cryptic but they map directly to schema.org spec.

Common warnings decoded:

• "Missing field 'image'" on Article schema — your image object is malformed. It needs @type: "ImageObject" with url, not just a string URL.
• "Missing field 'price'" on Product schema — check for whitespace in your offers price property. A space before "99.99" will fail. Yes, really.
• "Invalid value for 'review'" — your reviewRating is missing bestRating. If you set a rating of 5, Google needs to know the scale.

Step 4: The URL Inspection Tool

This is the only tool that shows you what Google actually parsed. Run the URL, click "View crawled page," and look at the structured data tab. If it's different from what you see in the Rich Results Test, Googlebot hasn't recrawled. Request indexing and wait 24 hours.

Step 5: Schema Markup Validator (Chrome Extension)

For quick debugging while browsing, the Schema Markup Validator extension highlights all schema on a page. I use it to verify breadcrumb schema on every page of a site in minutes.

One more thing: If you're using JSON-LD via a tag manager, Google sometimes doesn't execute GTM scripts before parsing schema. Inline it. Always.