An upgrade from ‘disco’ (19.04) to ‘focal’ (20.04) is not supported with this tool.

Unfortunately once a version of Ubuntu becomes unsupported you can run into problems upgrading to the latest version. As is the case when you try to upgrade disco to focal. Ubunut 19.04 to 20.04.

A work around is to update the apt sources and then run an update

Update Apt Sources with.

sudo sed -i 's/disco/focal/g' /etc/apt/sources.list

Now Upgrade with the following two commands.

sudo apt update
sudo apt -y dist-upgrade

More info at the following link.

Install NextCloud on Ubuntu 19.04

Install with snap

sudo snap install nextcloud 

Set user and password for NextCloud

sudo nextcloud.manual-install nextcloudadmin password

Allow https access for firewall

sudo ufw allow 80,443/tcp

For the following steps to work, you’ll need an A record setup on your domain name server to point a domain to your Next Cloud servers public ip address. Change in the following steps to the domain name you’ve setup.

View trusted domains

sudo nextcloud.occ config:system:get trusted_domains

Setup new trusted domain. Change with your domain.

sudo nextcloud.occ config:system:set trusted_domains 1

Run through Lets Encrypt to setup a SSL certificate.

sudo nextcloud.enable-https lets-encrypt

Should be able to access NextCloud from a web browser

Extra info

Set static ip address in Ubuntu 19.04

The network configuration settings for the server edition of Ubuntu are now stored in the following location. Create the file if it does not exist.

sudo vi /etc/netplan/01-network-manager-all.yaml

Add or edit the config file to the following. Change eno1 to your interface name and the address and gateway to the appropriate IP’s

For more information, see netplan(5).
   version: 2
   renderer: networkd
      dhcp4: no
      addresses: []
        addresses: [,]

Now apply the changes with the following command.

sudo netplan apply