Why is my itemprop='image' markup incorrect?

schema.org/BlogPosting image permits ImageObject and URL, however Google only permits ImageObject, hence the error. The intended markup is:

<!-- my code -->
<div itemprop="image" itemscope itemtype="http://schema.org/ImageObject">
  <img src="image.jpg" itemprop="url">
</div>

               

Another discrepancy is schema.org/ImageObject recommends contentUrl, but Google recommends url, hence my usage above.

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In response to your comment's code, your structure is still incorrect. I'll take it line by line:

<!-- your code -->
<div itemscope='itemscope' itemtype='http://schema.org/BlogPosting'>

Minor point, but unless you're going for XHTML, itemscope='itemscope' is wrong. Use itemscope (as you did later on).

<!-- your code -->
  <div itemprop='articleBody'>
    <div itemscope itemtype="http://schema.org/ImageObject"/>

Your ImageObject is a child of the articleBody property, but you haven't associated it in this way. Like this, you have an articleBody with no associated properties and an unassociated ImageObject. You should use

<!-- my code -->
    <div itemprop="image" itemscope itemtype="http://schema.org/ImageObject">

Also, /> is incorrect, even if you are trying for XHTML as this element does have children and a closing </div>. Just use > as I included in the above snippet.

<!-- your code -->
      <a href="1.png" itemprop="url"><img itemprop="image sharedContent" src="1.png" /></a>

What is sharedContent doing here? sharedContent expects a CreativeWork when used as a property of SocialMediaPosting — never as a property of ImageObject and never on an img.

Your other code snippet which places the sharedContent property as below is also wrong.

<!-- your code -->
<div itemscope='itemscope' itemtype='http://schema.org/BlogPosting'>
  <div itemprop='articleBody'>
    <div itemprop='sharedContent'>
      <div itemscope itemtype="http://schema.org/ImageObject"/>
        …

Whilst sharedContent is now in the right place, it still needs to be a CreativeWork. Your ImageObjects are still not associated with the BlogPosting, as shown by the Structured Data Testing Tool.

                                          

The following is the correct code.

<!-- my code -->
<div itemscope itemtype="http://schema.org/BlogPosting">
  <div itemprop="articleBody">
    <div itemprop="image" itemscope itemtype="http://schema.org/ImageObject">
      <a href="1.png" itemprop="url"><img itemprop="image" src="1.png"></a>
    </div>
    <div itemprop="image" itemscope itemtype="http://schema.org/ImageObject">
      <a href="2.png" itemprop="url"><img itemprop="image" src="2.png"></a>
    </div>
    <div itemprop="image" itemscope itemtype="http://schema.org/ImageObject">
      <a href="3.png" itemprop="url"><img itemprop="image" src="3.png"></a>
    </div>
  </div>
</div>

I had a similar problem with Google Structured Data Tester marking my images as invalid. Apparently it doesn't accept images where the source is a localhost domain. As soon as I deployed to the staging server the structured markup passed validation.