Spreedme - Service Unavailabl


i ve tried to install Nextcloud VM at a Ubuntu 16.04 Server with SSL Cert (https://github.com/nextcloud/vm). Nextcloud an the other apps are working perfectly but the SpreedMe App shows me only this:

Service Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Apache/2.4.18 (Ubuntu) Server at c.webundstyle.com Port 443

I ve got at the installation process this message:

Mount snap “core” (3247) ([start snap-core-3247.mount] failed with exit status 1: Job for snap-core-3247.mount failed. See “systemctl status snap-core-3247.mount” and “journalctl -xe” for details.

Can anybody help?