SEOLZ

Non iso date

Moderate effort

Found on 1% of audited stores.

Change all datePublished (and dateModified) values in your structured data from informal formats like "09/23/2019 00:00:00" to the ISO-8601 format "2019-09-23" so search engines can correctly read your content's publication date.

What it is

Structured data (the behind-the-scenes code that tells Google what your page is about) includes date fields like `datePublished` and `dateModified`. These dates must be written in a specific international format called ISO-8601 — which looks like `YYYY-MM-DD` (for example, `2019-09-23`) or with a full timestamp like `2019-09-23T00:00:00Z`. When dates are written in a casual format like "09/23/2019 00:00:00" or "September 23, 2019", search engines cannot reliably parse them and may ignore them entirely. Think of it like filling out an official form: the field has a required format, and anything else gets rejected.

Why it matters

Google uses `datePublished` and `dateModified` to understand content freshness — a key signal for ranking pages in news, article, product, and general search results. If Google can't parse your date, it may estimate the wrong publish date or show no date at all in search results, making your listings look outdated or untrustworthy compared to competitors whose dates are formatted correctly. For Answer Engine Optimization (AEO), freshness signals help your content surface in AI-generated answers and featured snippets, where recency is often a deciding factor. A malformed date can also cause your structured data to fail Google's Rich Results Test, disqualifying your pages from rich result enhancements like breadcrumb trails, review stars, and FAQ dropdowns — all of which directly impact click-through rates and organic traffic.

How to fix it

  1. Identify all structured data blocks on your site (JSON-LD scripts, Microdata, or RDFa) that contain date fields such as datePublished, dateModified, dateCreated, or startDate.
  2. Check the current value of each date field — any format that isn't YYYY-MM-DD or a full ISO-8601 datetime (e.g. 2019-09-23T00:00:00Z) must be corrected.
  3. Rewrite each offending date value in ISO-8601 format: date-only as YYYY-MM-DD (e.g. 2019-09-23), or with time and timezone as YYYY-MM-DDTHH:MM:SSZ (e.g. 2019-09-23T00:00:00Z).
  4. Save and publish the updated structured data, then paste the page URL into Google's Rich Results Test to confirm the dates are now parsed without errors or warnings.
  5. If dates are generated dynamically by your platform or theme (rather than hard-coded), locate the template or plugin responsible and update the date-output format at the source so all future pages are also correct.
  6. Re-submit updated pages to Google Search Console via the URL Inspection tool to prompt faster re-crawling of the corrected structured data.
{
  "@context": "https://schema.org",
  "@type": "WebPage",
  "name": "My Product Page",
  "datePublished": "2019-09-23",
  "dateModified": "2024-03-15T09:30:00Z"
}

Fix it on your platform

Pick your platform for the exact steps.

How to fix non iso date on Shopify
  1. In your Shopify admin, go to Online Store → Themes → click 'Edit code' on your active theme.
  2. Search for 'datePublished' or 'dateModified' across theme files using the search box — these are most commonly in 'article.liquid', 'product.liquid', 'page.liquid', or a dedicated 'structured-data.liquid' snippet.
  3. Find the Liquid output tag generating the date (e.g. {{ article.created_at }}) and wrap it in a date filter to enforce ISO-8601 format: {{ article.created_at | date: '%Y-%m-%dT%H:%M:%SZ' }}
  4. Repeat for dateModified using the updated_at object property: {{ article.updated_at | date: '%Y-%m-%dT%H:%M:%SZ' }}
  5. Save the file and verify using Google's Rich Results Test (search.google.com/test/rich-results) on a page that uses the template.
  6. If you use a third-party SEO app (e.g. Yoast for Shopify, JSON-LD for SEO, Smart SEO), check that app's structured data settings/output to ensure it is also generating ISO-formatted dates.
Full Shopify guide →Official Shopify docs ↗
How to fix non iso date on WooCommerce
  1. Install and activate the 'Yoast SEO' or 'Rank Math SEO' plugin if not already present — both output ISO-8601 dates automatically for most schema types.
  2. If you have custom or theme-generated JSON-LD, go to Appearance → Theme File Editor (or use a child theme) and locate the file outputting structured data — often 'functions.php', 'single-product.php', or a dedicated schema file.
  3. Find any PHP date output and replace informal formats with: date('Y-m-d\TH:i:s\Z', strtotime($date_string)) or use WordPress's built-in: get_the_date('Y-m-d\TH:i:s\Z').
  4. For Yoast SEO: Settings are mostly automatic; verify under SEO → Search Appearance → Content Types that the correct post/product types are enabled for schema output.
  5. For Rank Math: Go to Rank Math → Titles & Meta → Posts/Products and confirm Schema type is set; Rank Math handles ISO formatting natively.
  6. Test any updated product or post URL in Google's Rich Results Test to confirm dates pass without warnings.
Full WooCommerce guide →Official WooCommerce docs ↗
How to fix non iso date on BigCommerce
  1. In your BigCommerce admin, go to Storefront → Script Manager and check for any custom JSON-LD scripts injected site-wide — update any date strings to YYYY-MM-DD or YYYY-MM-DDTHH:MM:SSZ format there.
  2. Go to Storefront → Themes → click 'Edit Theme Files' (Advanced) on your active theme to open the Stencil theme editor.
  3. Search for 'datePublished' or 'dateModified' in template files (commonly in 'templates/pages/product.html', 'blog-post.html', or partials in 'templates/components/').
  4. BigCommerce Handlebars templates use helpers like {{format-date}} — replace any non-ISO date helper output with a correctly formatted ISO string: use {{date published format='YYYY-MM-DDTHH:mm:ssZ'}} if your theme/helper supports it, or hard-code a corrected helper.
  5. If your theme uses a third-party SEO app from the BigCommerce App Marketplace (e.g. SEO King, Yoast for BigCommerce), check that app's structured data output settings to ensure ISO dates.
  6. Validate a product and blog page in Google's Rich Results Test after changes.
Full BigCommerce guide →Official BigCommerce docs ↗
How to fix non iso date on Wix
  1. Wix generates most structured data automatically. Go to your Wix dashboard → Marketing & SEO → SEO Tools → Structured Data Markup to review any custom structured data you've added.
  2. If you added custom JSON-LD via Wix's 'Add Structured Data Markup' tool, click 'Edit' on any schema containing a date field and manually correct the value to ISO-8601 format (e.g. '2019-09-23' or '2019-09-23T00:00:00Z').
  3. For Wix Blog posts, Wix handles datePublished automatically in its built-in schema — ensure you're using the native Wix Blog feature rather than a custom workaround.
  4. For Wix Stores products, structured data dates are also handled natively. If you see malformed dates, check if a third-party app (installed via the Wix App Market) is overriding the default schema.
  5. If you're using Wix Velo (custom code), locate the relevant page's code panel and correct any date strings using JavaScript's toISOString() method: new Date(dateString).toISOString().
  6. Re-test affected pages in Google's Rich Results Test.
Full Wix guide →Official Wix docs ↗
How to fix non iso date on Squarespace
  1. Squarespace generates structured data for Blog Posts and Products automatically using its built-in schema templates — date formatting is handled by the platform natively in most cases.
  2. If you have injected custom JSON-LD via Settings → Advanced → Code Injection (site-wide header/footer) or via a page's Page Header Code Injection, review those scripts for any date fields.
  3. In the Code Injection editor, locate any date strings and manually update them to ISO-8601 format: '2019-09-23' or '2019-09-23T00:00:00Z'.
  4. If you use a third-party SEO extension (e.g. via Squarespace Extensions marketplace), check that extension's schema/structured data output settings.
  5. For Blog posts specifically, the published date Squarespace uses in its auto-generated schema is pulled from the post's published date set in the Blog Post Editor — ensure this is set correctly (Squarespace handles the formatting itself).
  6. Validate pages using Google's Rich Results Test after any code injection changes.
Full Squarespace guide →Official Squarespace docs ↗
How to fix non iso date on Webflow
  1. In the Webflow Designer, open the Page Settings for any page that has custom JSON-LD structured data added in the 'Custom Code' → 'Head Code' or 'Before </body> tag' sections.
  2. Locate any date fields in those JSON-LD blocks and correct the value to ISO-8601 format: '2019-09-23' or '2019-09-23T00:00:00Z'.
  3. For CMS-driven pages (Blog Posts, Products), open the CMS Collection schema under CMS → Collections, and check if you have a Date field connected to a JSON-LD embed in the Collection Template page.
  4. In the Collection Template page's custom code embed, use Webflow's CMS field binding to pull the date dynamically. Ensure the bound Date field outputs in ISO format — Webflow Date fields can be formatted; use the 'YYYY-MM-DD' format option in the embed binding dialog.
  5. If dates are hard-coded in embeds, update each one manually to the correct ISO format.
  6. Publish the site and test affected pages in Google's Rich Results Test.
Full Webflow guide →Official Webflow docs ↗
How to fix non iso date on Adobe Commerce (Magento)
  1. In your Magento admin, go to Content → Configuration → check if a third-party SEO extension (e.g. Mageplaza SEO, Amasty SEO, Mageworx SEO Suite) is responsible for generating structured data — if so, consult that extension's settings panel for date format options.
  2. If structured data is output by a custom theme, navigate to your theme directory on the server (app/design/frontend/<Vendor>/<theme>/) and search for 'datePublished' or 'dateModified' in .phtml or .xml layout files.
  3. Locate the PHP code generating the date value and replace informal formatting with PHP's DateTime output: (new DateTime($date))->format(DateTime::ATOM) which produces a valid ISO-8601 string.
  4. Alternatively, use PHP's date() function: date('Y-m-d\TH:i:s\Z', strtotime($date_value)).
  5. Clear the Magento cache after changes: System → Cache Management → Flush Cache Storage.
  6. Test product and CMS pages in Google's Rich Results Test to confirm corrected date output.
Full Adobe Commerce (Magento) guide →Official Adobe Commerce (Magento) docs ↗

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Frequently asked questions

What is Non iso date?

Structured data (the behind-the-scenes code that tells Google what your page is about) includes date fields like `datePublished` and `dateModified`. These dates must be written in a specific international format called ISO-8601 — which looks like `YYYY-MM-DD` (for example, `2019-09-23`) or with a full timestamp like `2019-09-23T00:00:00Z`. When dates are written in a casual format like "09/23/2019 00:00:00" or "September 23, 2019", search engines cannot reliably parse them and may ignore them entirely. Think of it like filling out an official form: the field has a required format, and anything else gets rejected.

Why does non iso date matter?

Google uses `datePublished` and `dateModified` to understand content freshness — a key signal for ranking pages in news, article, product, and general search results. If Google can't parse your date, it may estimate the wrong publish date or show no date at all in search results, making your listings look outdated or untrustworthy compared to competitors whose dates are formatted correctly. For Answer Engine Optimization (AEO), freshness signals help your content surface in AI-generated answers and featured snippets, where recency is often a deciding factor. A malformed date can also cause your structured data to fail Google's Rich Results Test, disqualifying your pages from rich result enhancements like breadcrumb trails, review stars, and FAQ dropdowns — all of which directly impact click-through rates and organic traffic.

How do I fix non iso date?

Change all datePublished (and dateModified) values in your structured data from informal formats like "09/23/2019 00:00:00" to the ISO-8601 format "2019-09-23" so search engines can correctly read your content's publication date.

Authoritative references

Related Answer Engine Optimization issues