There was an error converting your project.
Leopard only supports new projects (created in Scratch 3.0). And the only supported extension is "pen"; all others will fail.
If you aren't sure why your project is failing, ask on the forums!
Leopard translates your Scratch projects to JavaScript, which opens up a whole new world of programming possibilities.
Learn the basics of Leopard in this video from PullJosh
You can publish Leopard projects anywhere!