New certificate fails - certbot invalid response /.well-known/acme-challenge

Question

I have installed on my raspberry pi apache and wanted to create a new certificate for my domain.

I have created my domain via no-ip and configured the dyndns in the fritzbox settings. I have also created a virtual host and installed certbot with the follwing link: https://certbot.eff.org/instructions?ws=apache&os=debianstretch

But while executing ""sudo certbot --apache"" I get the following error message:

Certbot failed to authenticate some domains (authenticator: apache). The Certificate Authority reported these problems:   Domain: ""Domain deleted""   
Type:   unauthorized   
Detail: ""Domain deleted"": Invalid response from http://""Domain deleted""/.well-known/acme-challenge/HTptNJcGtYB1e0I7jfNU-a8hAeY2upza0daUrEWP0Po: 404

Hint: The Certificate Authority failed to verify the temporary Apache configuration changes made by Certbot. Ensure that the listed domains point to this Apache server and that it is accessible from the internet.

I have tried a lot with some hints but none of these worked for me. Is there anybody who could help me?

Thanks in advance :)