Settings says there are problems with your installation. That yellow list is a checklist written by the server itself - here is what each common line means and the exact command that clears it.
Open Settings - Overview on a fresh install and Nextcloud greets you with a list of security and setup warnings. New admins read it as an error; it is actually the server's own to-do list, and most lines clear with one command through the snap's occ tool, sudo nextcloud.occ. Work through them in the order below. A warning is not the server failing - it is the server asking for a finishing touch, and an empty list is a genuinely well-kept install.
Two related lines appear as an install ages and are normally fixed together:
sudo nextcloud.occ db:add-missing-indices. It can take a while on a big install; let it finishsudo nextcloud.occ db:convert-filecache-bigint, best run while users are quiet. On current versions this one is largely historicalBoth are housekeeping, not damage - the database grew features faster than the tables did, and these commands bring them up to date.
Two one-line settings clear two stubborn warnings:
sudo nextcloud.occ config:system:set default_phone_region --value=IN (use your own country code)sudo nextcloud.occ config:system:set maintenance_window_start --type=integer --value=2If the panel says the PHP memory limit is below the recommended 512 MB, the snap answers with its own style of setting instead of a php.ini edit:
sudo snap set nextcloud php.memory-limit=512Msudo snap restart nextcloudThe snap pre-tunes most PHP settings including the OPcache, so warnings in that family are rare on this route - if one appears right after a big update, a snap restart clears it more often than any edit does.
This warning is about reachability, not storage: without an email server, Nextcloud cannot send password-reset mails, share notifications or activity summaries. Configure it in Settings - Basic settings - Email server with your mail provider's SMTP details and send the test email the page offers. A home server with no outside users can honestly leave this one - but the day someone forgets a password with no admin nearby, you will wish you had not.
General Nextcloud advice warns about things this install route settles for you, which is worth knowing so you do not fix what is not broken:
After each fix, reload the Overview page - the list re-checks itself, and watching lines disappear is the proof the commands landed.
The one-step install in the video, then this list - the complete finishing routine.
Watch Full VideoMost are optimisation and hardening notices, not holes - the server runs fine with them present. Treat them as a quality checklist: fix them in a quiet half hour, and prioritise anything the panel itself words as a security item.
Usually one of two reasons: the fix needs a restart to register (restart the snap and reload the page), or a version upgrade reintroduced the item with a fresh fix. Re-run the matching occ command - they are safe to repeat.
Not at home or small-office scale. The snap's built-in local cache is the standard configuration for installs of this size; Redis enters the picture on large multi-server deployments.