Nginx proxy manager problem when request a cert

i tried to add a nginx proxy manager but it fails all the time with internal error.

6/23/2024] [12:53:00 PM] [Express  ] › ⚠  warning   Command failed: certbot certonly --config "/etc/letsencrypt.ini" --work-dir "/tmp/letsencrypt-lib" --logs-dir "/tmp/letsencrypt-log" --cert-name "npm-5" --agree-tos --authenticator webroot --email "[email protected]" --preferred-challenges "dns,http" --domains "joker.duckdns.org" 
Saving debug log to /tmp/letsencrypt-log/letsencrypt.log
Some challenges have failed.
Ask for help or search for solutions at https://community.letsencrypt.org. See the logfile /tmp/letsencrypt-log/letsencrypt.log or re-run Certbot with -v for more details.

this is my setup in the UI

i don t get the problem. what is wrong?

[email protected] is not a domain name !

sorry.
copy paste problem.
i tries it with the right duckdns adress. just to anonymize my account

http://joker.duckdns.org does not seem to redirect to a valid host. So, Certbot’s http challenge fails.

[6/23/2024] [2:09:36 PM] [Express ] › :warning: warning Requested name http://joker.duckdns.org appears to be a URL, not a FQDN. Try again without the leading “http://”.

hmm?

Certbot’s http challenge requires that a host or server is answering on your domain name.

I don’t know what happened but one day later it was no problem to get the certificates and now the system is running fine