@li-an
Your HTML tag is not what it should be if you are only using AMP 0.4. This Tag is defined is the single.php template of the plugin with that:
<html amp <?php language_attributes(); ?>>
So you should have that:
<html amp lang="fr-FR">
But you have that:
<html amp lang="fr-FR"
itemscope
itemtype="https://schema.org/Article"
prefix="og: https://ogp.me/ns#" >
Wich is not correct and it’s the reason why you get this validating error : “The attribute ‘prefix’ may not appear in tag ‘html ? for top-level html”
Are you using any other AMP plugin like Glue Yoast or others?
Did you cleared you Comet Cache?
Can you please disable Comet Cache for this posts?
The last error you get is: “The mandatory tag ‘html ? for top-level html’ is missing or incorrect.”
> I think this is an error that come from the first error you get…
PS: je suis aussi fran?ais ??