SharePoint requires HTML files to be XML-compliant. Your file isn't XML-compliant, likely because of tag properties without ...

SharePoint requires HTML files to be XML-compliant. Your file isn't XML-compliant, likely because of tag properties without quotes, missing closing tags, or invalid properties in tags. 

{0}

Occurred at: {1}

Run the file through an XML validator, fix any issues using your HTML editor, save the file, and refresh this preview.