nextcloud-ng_backup/docs/DISASTER-RECOVERY.md

Disaster recovery: your server is gone

Your Nextcloud server is lost. You have a new, empty server. These are the steps to get your Nextcloud back from an NG Backup location. Do them in this order.

What you need

• The recovery kit file (ng_backup-kit.json) and one passphrase of it.
• The connection details of the backup location: host, user, password or keys, bucket, folder.
• A new server with the same Nextcloud major version as the old one (for example 34), a database (PostgreSQL, MySQL/MariaDB or SQLite; it may differ from the old one) and room for the whole backup plus a margin.
• A list of the apps that are not in the app store (your own builds, apps copied in by hand). Keep their packages somewhere safe beforehand.

No kit? If the location still holds its config file, the key is there too, but this version can only import it from a kit. Keep the kit off the server, next to the passphrase.

Steps

1. Install a fresh Nextcloud of the same major version. Create an admin account. Do not add users or files.

2. Do not let background jobs run yet. A new Nextcloud runs them on page visits (AJAX). Switch that off:

occ background:cron

As long as no cron is set up, nothing runs. Check that none is:

• Regular server: sudo crontab -u www-data -l. If it shows a line with cron.php, remove it for now with sudo crontab -u www-data -e (put it back in step 9).
• Docker Compose with a cron service: docker compose stop cron.
• Nextcloud All-in-One: cron runs inside the Nextcloud container; leave it. It does no harm here: the restore keeps NG Backup's own settings of the new server, so it does not start backups.

This keeps the new server quiet (no mail syncs, no notifications, no backups) until it is ready.

3. Install NG Backup (the same version or newer) and enable it.

4. Import the backup key. Copy the kit to the new server so the web server user can read it.

From your own computer:

scp ng_backup-kit.json root@newserver:/tmp/

Then on the server, one of:

chown www-data /tmp/ng_backup-kit.json                                    # regular server
docker cp /tmp/ng_backup-kit.json <container>:/tmp/ && \
  docker exec <container> chown www-data /tmp/ng_backup-kit.json          # Docker

<container> is the name of your Nextcloud container: docker ps shows it (for example nextcloud-aio-nextcloud, or myproject-nextcloud-1 with Docker Compose).

Import it; you type the passphrase yourself:

occ backup:key:import /tmp/ng_backup-kit.json

It shows the key fingerprint: it must match the one of your old server (on the recovery kit).

5. Add the backup location with the same details as before. This can take a while on a large backup (the index is read first) and shows nothing until it is done.

occ backup:target:add offsite sftp -a password::password -o host=... -o user=... -o password=... -o root=... --path=...

If it says "No backup key yet", the key is not imported. Run step 4:

occ backup:key:import /tmp/ng_backup-kit.json

Do not run backup:key:init, even though the message suggests it: that makes a brand new key, and your backups were encrypted with the old one. NG Backup then refuses the location ("created with a different key").

6. List the restore points and pick one, normally the newest:

occ backup:list offsite

7. Install the apps the old server had. Run the restore; before it changes anything it checks the apps and stops with what is missing:

occ backup:restore:full offsite <snapshot>

• "install these apps first: …": install each from the app store (occ app:install <app>), or enable it if it is part of Nextcloud but switched off (occ app:enable <app>, for example admin_audit). Apps that are not in the app store: copy them into custom_apps and enable them.
• "Table … does not exist here": an app that was removed or switched off long ago left tables behind. Install that app (for example deck, onlyoffice), then run the restore again.

Repeat until the restore starts.

8. Let the restore run. It restores the database, then the data directory, and takes hours for a large backup. If it stops halfway, fix the cause and run the same command again with --force.

9. After the restore

• Check config/config.php: trusted_domains, overwrite.cli.url, and the cache (Redis) host must match the new server. The database settings and data directory are kept from the new installation.
• occ upgrade (apps on the new server may be newer than in the backup), then occ maintenance:repair.
• Log in, open some files, a calendar and a contact.
• Start background jobs (cron).

10. Point your domain at the new server and check that clients reconnect.

11. Make a backup of the new server to the same location (occ backup:run offsite). The old server must stay off: two servers must never write to the same location.

Never

• Never let the old server write to the location again if it comes back. Switch its backups off first.
• Never give your passphrase to anyone. Nobody helping you needs it.

Help

Stuck? Ensembia, the developer of NG Backup, offers paid help with restoring a backup after a crash.