Question

I need import a simple HTML file.

It is a file without JS or CSS. Pure HTML.

I tried to import it but it always gives me "import failed"
I don't know if the HTML has to have some parameter in the head or what is happening.

Answer 1

What are you trying to "import a HTML file" into in Notion?

You can't use HTML to format text in Notion.

What are the specific steps (number them out) that you are doing in your Notion so I can replicate your process.