So spaceinvader has a few videos on how to fix the errors that you in nextcloud
There are some warnings regarding your setup.
The reverse proxy header configuration is incorrect, or you are accessing Nextcloud from a trusted proxy. If not, this is a security issue and can allow an attacker to spoof their IP address as visible to the Nextcloud. Further information can be found in the documentation.
The "X-Frame-Options" HTTP header is not set to "SAMEORIGIN". This is a potential security or privacy risk, as it is recommended to adjust this setting accordingly.
The "Strict-Transport-Security" HTTP header is not set to at least "15552000" seconds. For enhanced security, it is recommended to enable HSTS as described in the security tips ↗.
The database is missing some indexes. Due to the fact that adding indexes on big tables could take some time they were not added automatically. By running "occ db:add-missing-indices" those missing indexes could be added manually while the instance keeps running. Once the indexes are added queries to those tables are usually much faster.
Missing index "calendarobject_calid_index" in table "oc_calendarobjects_props".
Missing index "schedulobj_principuri_index" in table "oc_schedulingobjects".
Some columns in the database are missing a conversion to big int. Due to the fact that changing column types on big tables could take some time they were not changed automatically. By running 'occ db:convert-filecache-bigint' those pending changes could be applied manually. This operation needs to be made while the instance is offline. For further details read the documentation page about this.
mounts.storage_id
mounts.root_id
mounts.mount_id
Please double check the installation guides ↗, and check for any errors or warnings in the log.
Check the security of your Nextcloud over our security scan ↗.
Since this is not a LSIO container you can use user abc to run them, does anyone know what is the user that had access to www-data? so the problems can be fixed.