Schema itemprop attributes are marked as invalid, how to fix it?

Question

In my current WordPress theme, I have implemented Microdata (using Schema.org) for every possible element. But after I have run markup validation on validator.w3.org, it's showing 21 errors on only itemprop attributes.

The errors are:

Validation Output: 21 Errors

Error Line 76, Column 131: The itemprop attribute was specified, but the element is not a property of any item.

…op="mainContentOfPage" itemscope="itemscope" itemtype="http://schema.org/Blog">

✉
Error Line 78, Column 225: The itemprop attribute was specified, but the element is not a property of any item.

…scope="itemscope" itemtype="http://schema.org/BlogPosting" itemprop="blogPost">

✉
Error Line 81, Column 44: The itemprop attribute was specified, but the element is not a property of any item.

…lass="entry-title" itemprop="headline"><a href="http://www.bloggingspell.com/a…

✉
Error Line 86, Column 42: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-thumb" itemprop="image">

✉
Error Line 91, Column 43: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-summary" itemprop="text">

✉
Error Line 100, Column 213: The itemprop attribute was specified, but the element is not a property of any item.

…scope="itemscope" itemtype="http://schema.org/BlogPosting" itemprop="blogPost">

✉
Error Line 103, Column 44: The itemprop attribute was specified, but the element is not a property of any item.

…lass="entry-title" itemprop="headline"><a href="http://www.bloggingspell.com/a…

✉
Error Line 108, Column 42: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-thumb" itemprop="image">

✉
Error Line 113, Column 43: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-summary" itemprop="text">

✉
Error Line 122, Column 224: The itemprop attribute was specified, but the element is not a property of any item.

…scope="itemscope" itemtype="http://schema.org/BlogPosting" itemprop="blogPost">

✉
Error Line 125, Column 44: The itemprop attribute was specified, but the element is not a property of any item.

…lass="entry-title" itemprop="headline"><a href="http://www.bloggingspell.com/m…

✉
Error Line 130, Column 42: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-thumb" itemprop="image">

✉
Error Line 135, Column 43: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-summary" itemprop="text">

✉
Error Line 144, Column 229: The itemprop attribute was specified, but the element is not a property of any item.

…scope="itemscope" itemtype="http://schema.org/BlogPosting" itemprop="blogPost">

✉
Error Line 147, Column 44: The itemprop attribute was specified, but the element is not a property of any item.

…lass="entry-title" itemprop="headline"><a href="http://www.bloggingspell.com/s…

✉
Error Line 152, Column 42: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-thumb" itemprop="image">

✉
Error Line 157, Column 43: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-summary" itemprop="text">

✉
Error Line 166, Column 230: The itemprop attribute was specified, but the element is not a property of any item.

…scope="itemscope" itemtype="http://schema.org/BlogPosting" itemprop="blogPost">

✉
Error Line 169, Column 44: The itemprop attribute was specified, but the element is not a property of any item.

…lass="entry-title" itemprop="headline"><a href="http://www.bloggingspell.com/a…

✉
Error Line 174, Column 42: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-thumb" itemprop="image">

✉
Error Line 179, Column 43: The itemprop attribute was specified, but the element is not a property of any item.

<div class="entry-summary" itemprop="text">

I have implemented the Microdata by following the sites yoast.com and bloggingwizard.com. These two are showing valid on W3C validator but my site is not. Can anybody help me with this issue?

Here is the URL of validation check:

http://validator.w3.org/check?uri=http%3A%2F%2Fwww.bloggingspell.com%2F&charset=%28detect+automatically%29&doctype=Inline&group=0

And here is my site:

http://www.bloggingspell.com/

My theme: Crangasi

Solution

You have an itemprop on your main element, but there is no parent item to which this property belongs to.

As you are using mainContentOfPage, you probably want to have a WebPage item. But note that this property can’t have Blog as value, it needs to be a WebPageElement.

So you might want to remove itemprop="mainContentOfPage" from main.