I embedded a demo video on my landing page and added VideoObject structured data so it could show up as a rich result in Google search. I ran it through Google's Rich Results Test, and the headline was good: valid, one item detected, eligible for rich results. But sitting right next to that green checkmark were two orange warnings, both pointing at the same property — uploadDate.
The two complaints were:
- "invalid value for uploadDate"
- "the uploadDate datetime is missing a timezone"
I'd written the field the obvious way:
"uploadDate": "2026-08-15"
That looks like a perfectly good date, and for a human it is. But structured-data dates are expected to follow ISO 8601, and a bare calendar date — year-month-day with nothing else — isn't an actual moment in time. There's no hour, and there's no timezone, so Google can't pin it to a specific instant on a timeline. Hence both warnings: the value is technically incomplete, and specifically it's missing the timezone piece.
The fix is to give it a full datetime with an offset:
"uploadDate": "2026-08-15T00:00:00+00:00"
The T separates date and time, and the +00:00 (UTC) is the timezone offset. You could also write it as ...Z. As soon as I did that, both warnings disappeared and the rich-result eligibility stayed exactly as it was. Same rule applies to datePublished and dateModified in Article/BlogPosting schema — if you're feeding those a bare date, they'll trip the same warning, and the same T…offset fix clears them.
One thing worth saying plainly: these were warnings, not errors. My video was already eligible for a rich result even with the bare date. So this wasn't a "my thing is broken" situation — it was a "my thing works but there's a yellow light on the dashboard" situation. I still fixed it, for two reasons: a clean schema is more likely to be interpreted the way I intend, and a quiet Search Console report means the next real problem actually stands out instead of hiding in a pile of ignored warnings. Cheap win, so I took it.
The video itself was a demo of NotebookBloom — a Chrome extension that turns NotebookLM (now also called Gemini Notebook) into a research workspace: citation export (APA/MLA/Chicago/BibTeX), Anki flashcard export with the source attached, and cross-notebook search. It's on the Chrome Web Store and my site.
If Google's Rich Results Test ever tells you a date is "invalid" or "missing a timezone": you almost certainly handed it a bare YYYY-MM-DD. Add the time and the offset, and move on.
Site: https://notebookbloom.com · Chrome Web Store: https://chromewebstore.google.com/detail/fmnhogknjhlaicceielblddajjabjlha
— building NotebookBloom in public
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