**You are getting this error because “some” or “all” your Structured Data definitions are referring to Data-vocabulary.org instead of schema.org****.** (https://schema.org/)
It is very likely that issue is coming on your breadcrumb as we all used to just copy that definition earlier, which referred to a “now deprecated” vocabulary.
You are referring to a data-vocabulary. (https://data-vocabulary.org/)org (which is now deprecated) for your SD, and not schema.org. You need to use the JSON-LD structure Data format in order to get rid of this error. First, you need to visit schema.org website and scroll down to find the data format tab with JSON-LD structure (recommended by Google) and find the right vocabulary property as per schema.org.
You can access google search console => Advanced features => Links to see if your website receives notifications about changes in data structure “Data-vocabulary” or not. Switching to the schema.org structure will make your web articles more detailed and richer with Google’s search engine.
To know if your web structure is “Data-vocabulary” or schema.org, use the Structured data Testing tool (https://search.google.com/structured-data/testing-tool/u/0/) provided by Google and type a URL to test for any SD related errors.
For example, if you are using a data.vocabulary as your data structure vocabulary, then you will find the following in your breadcrumb
itemtype=”https://data-vocabulary.org/Breadcrumb (https://data-vocabulary.org/Breadcrumb)
This is exactly why you are getting this error. You may plan to use RDFa or Microdata, however, you are referring to a data-vocabulary for your SD, which is now deprecated.
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