A <meta> element without a itemprop or property attributes has been found in an unexpected place.
While the <meta> element is commonly used within the <head> section of the document, it can also be used within the <body> section, for example in the context of defining microdata, as in this example:
<div itemprop="offers" itemscope itemtype="http://schema.org/Offer">
Price: $<span itemprop="price">1.00</span>
<meta itemprop="priceCurrency" content="USD" />
</div>
When used within the <body> section, the <meta> element is required to have a itemprop or property, and a content attribute, and it can’t have a http-equiv or charset attribute.
A common cause for this issue is including a <meta> element that was intended for the <head> section (for example one containing a http-equiv attribute in the <body> , for example:
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<form>
...
</form>