The mandatory attribute ‘?’ is missing in tag ‘html’.

Hello @passegua

Thank you for contacting us, not sure if you checked the non-AMP version of your page.

Your AMP page can be found on: https://www.sinapsi.org/wordpress/?amp=1

notice that your site contains /wordpress/ in URL also the amp version can be found with ?amp=1 as a query parameter.

Here is the AMP validation test which says your AMP page is valid.

I hope this helps!

Thanks a lot