If you want more flexibility in the HTML that you are using on your website you can disable the XHTML validation for the publishing approval process.To do this open the Content Editor and in the tree view navigate to the /sitecore/System/Settings/Validation Rules/Global Rules item.As the web evolved and new demands emerged, the HTML5 standard has been published.HTML5 not only added new capabilities to HTML but also changed the main philosophy behind HTML.Rather than using the strict XML grammar as XHTML did, HTML5 allows developers to decide for themselves whether they want to have their HTML XML-compliant or not.
Consider the following webpage: It’s a perfectly valid HTML5 document.
Sitecore tries to help you maintain the quality of your website but sometimes it gets in your way.
Sitecore is a rich platform with powerful web content management capabilities.
Next time you will approve an item for publishing, the XHTML validation will not be executed and you will be able to publish your items even if your layouts or renderings use non-XHTML compliant HTML markup.
Sitecore tries to help you maintain the quality of your website by automatically validating your HTML when approving items for publishing.