Nextcloud GUI no longer available after certificate exchange

Hello dear Nextcloud community,

I need your help. I have registered a certificate on my new domain using Lets Encrypt, everything worked fine. Now that I have correctly stored this in /etc/ssl and adjusted the default-ssl.conf in /etc/apache2/sites-available with the new certificate path and restarted apache2, only an index of / appears when I try to access the GUI (see screenshot).

image

I have already stored my new domain under trusted domains. I have also restarted my Nextcloud several times - unfortunately in vain. Since I got stuck in troubleshooting here, I have already imported a snapshot, because I may have messed up the config. But that was not the case. Even after that I have the same problem.
Can you help me here?

Kind regards
Peter

UPDATE:

I was able to fix the problem. The Nextcloud folder was suddenly no longer in the var/www/html directory, I have now corrected this.

the ticket can be closed!