ERROR: Cannot locate specified Dockerfile

I raise my question as a new one here.

howto/preview-using-custom-domains-and-ssl-with-lets-encrypt-and-traefik/24133/10?u=miwa

I’ve got this error, anyone has an idea how I can fix this??

スクリーンショット 2020-09-23 18.51.44788×238 23.7 KB

Thanks!