I am trying to mark a blog with schema.org metadata (using Microdata). I have tested with the test tool at https://developers.google.com/structured-data/testing-tool/ and I get an error saying:image:   missing and requiredI am using BlogPosting schema, but I have pages without images.Why is an image mandatory and what should I do if I don't have one? Is it okay to have no tag, or is there some way to show there is no image?
Schema.org BlogPosting and image required
images;blog;schema.org
Schema.org does not require any properties, so having a BlogPosting without an image property is totally fine. (And, other than omitting the property, there is no way to denote that you dont have an image.)(Id even guess that not providing an image would be the norm, as the image property is not for just any image that is contained in the blog post, but for an image of, or an image that represents, the blog post itself.)The fact that Google reports this error in their Structured Data Testing Tool does not mean that the code would be invalid or that you would have to fix anything. (Ideally Google would mark these as informational, or warnings, but not as errors.)It just means that Google wont provide an Article Rich Snippet for your blog post in their results, as the image property is required for that, according to their documentation.If you just want to check your Microdata and dont care about Google-specific stuff (like their Rich Snippets), have a look at alternative tools: Online Microdata parser (Software Recommendations SE).