A breadcrumb trail on a page shows the page's position in the site hierarchy, which can assist users in better understanding and navigating a site. Starting from the last breadcrumb in the breadcrumb trail, a user can browse all the way up the site hierarchy, one level at a time.

• Determine which of your site's products generates the breadcrumb markup.
• Check to see whether the problem is in the SEO breadcrumb markup.
• Find and correct the error's source.
• Check Google Search Console to see if the remedy worked.

Read More: How can I solve ‘temporarily unreachable’ in Google Webmaster?