Occ: Additional task after update are not available

Nextcloud version: 18.0.4
Operating system and version: openSUSE LEAP 15.1
Apache or nginx version: Apache 2.4.33
PHP version: 7.2.5

After update to the version above (via Web-UI) a few weeks ago I see some hints in Admin/Overview they say that there are some indices are not automaticlly inserted. I have to run: occ db:add-missing-indices.

So today I go to the CLI, step into folder …/nextcloud and run:

sudo -i wwwrun php occ db:add-missing-indices

but I get the message:
Nextcloud is not installed - only a limited number of commands are available
There are no commands defined in the “db” namespace.

But it seems that NC is running properly …

Is this the first time you’ve seen this error? Yes

The output of your Nextcloud log in Admin > Logging:

Warning	appstoreFetcher	Could not connect to appstore: cURL error 6: Could not resolve host: api.nextcloud.com (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)	

… and indeed even a manual dig does not give any ip-Address for that host.

The the corresponding output of the Apache.log:

[Sun May 31 10:11:51.595043 2020] [authz_core:error] [pid 4686] [client]  AH01630: client denied by server configuration: /srv/www/htdocs/vhosts/<configDir>/nextcloud/data/.ocdata

The mentioned file (.ocdata) is empty …

What should I check next?