How to Migrate from TrueNAS CORE to SCALE Safely

Here is how to migrate from truenas core to scale safely: back up your data and configuration, clean-install Linux-based TrueNAS on the boot SSD, restore the CORE configuration, and check every service before reconnecting clients. The existing ZFS data pool can stay in place. This follows the documented community migration procedure.

How to migrate from CORE to SCALE: choose the supported route

Current documentation calls the Linux-based destination TrueNAS Community Edition. Start with the release recommended for general users on the Software Status page, which also maintains the upgrade chart. Avoid treating an old tutorial’s patch number as today’s recommendation.

Route	Supported sequence	Practical verdict
Clean install	Supported CORE maintenance release → destination ISO → restore configuration	Recommended for a straightforward home NAS.
In-place update	CORE → 24.04 → 24.10 → 25.04 → 25.10	More upgrade stages and reboots to supervise.

The migration guide requires updating your CORE branch to its latest maintenance release first. Direct CORE-to-24.10-or-later migration through the UI is unsupported. Read the blockers below before updating CORE, especially if your installation is old enough to use GELI.

Who this is for / who should skip

This guide suits a home NAS whose essential workload is file sharing. Reserve a maintenance day after backups finish; that is a planning allowance, not a measured migration time. If your only working application lives in a jail, rebuild and restore that application separately before committing to the NAS cutover.

Review the official migration preparation checklist:

• GELI encryption: stop and migrate data to non-GELI storage before OS upgrades. Saving keys alone does not make GELI compatible.
• Jails and plugins: do not migrate; preserve application settings and data for rebuilding.
• VMs: UEFI-configured guests can migrate; GRUB-configured guests cannot. Check devices and networking before starting them.
• Old configuration: remove SMB auxiliary parameters; review tunables, scripts, deprecated services, and user UID/GID conflicts.

Enterprise and HA systems need the vendor’s migration assistance.

Hardware that works

Keep the existing NAS chassis if its hardware meets the destination requirements. The installation guide specifies an x86_64 processor, at least 8 GB RAM, and a 20 GB boot device. Have local console access and identify the boot SSD by model and serial number. Leave hardware shopping and application consolidation for another weekend.

Storage and backups before touching the installer

In CORE, open System → General → SAVE CONFIG and select Export Password Secret Seed. Save the download on your laptop and in protected backup storage outside this NAS. The seed preserves access to encrypted configuration fields; CORE’s configuration backup documentation also calls for separate SSH-key backups.

Export dataset encryption keys and securely record passphrases separately. A configuration download is a settings database, not your files, and ZFS passphrases are never included.

Use a separate NAS as the data-backup target. For another TrueNAS system, remote snapshot replication preserves a copy on another machine. Include child datasets and application data. Quiesce databases and stop writers before the final backup.

Perform a restore drill: recover representative files into a scratch directory, open them from a client, and compare permissions and contents. Restore an application’s database backup too if that application matters. A completed transfer is encouraging; a usable restore is the point. Our snapshot and replication guide covers ongoing retention.

Finish a scrub and investigate reported pool errors before proceeding. Scrubs check pool integrity; they do not replace the separate backup.

Install, restore configuration, and import the pool

After clearing the blockers, update CORE to its supported maintenance release and export a fresh configuration. Record share paths, users, networking, and scheduled jobs. Confirm the old root credentials work before shutdown.

1. Download the destination ISO and verify its checksum. Write the installer USB, shut down CORE cleanly, and boot the installer.
2. Choose Install/Upgrade, then select only the boot SSD. The clean installation erases the selected drive. Never select a data-pool disk. These steps follow the installation instructions.
3. Create the installer administrator account, complete installation, remove the installer media, and reboot.
4. Sign in, open System → Advanced Settings → Manage Configuration → Upload File, and upload the saved CORE configuration. Allow the restart.

Expect the login to change. Restoring a CORE configuration removes the installer-created administrators. Log in using the old CORE root credentials, recreate an administrator, verify that account works, then disable root password login again. This is documented configuration-restore behavior.

Check Storage for the original pool. If it is absent, use Storage → Import Pool, select the detected pool, and import it. Unlock encrypted datasets with their saved credentials. Do not create a replacement pool on those disks or force an import from the shell: TrueNAS supports pool imports through its UI or API.

Networking and service checks

If the UI disappears, use the local console to correct the primary interface and address. FreeBSD and Linux interface naming differs; network settings can fail to transfer. Verify gateway, DNS, share addresses, and TLS access before changing anything else.

Test SMB/NFS access using ordinary client accounts: read files, create a test file, and confirm restricted directories remain restricted. Check ownership before attempting recursive permission changes.

Keep administration private. For existing remote access, a Tailscale subnet router on another machine can reach the NAS while applying Tailnet access policy. It also adds a dependency to maintain; local console access remains essential during migration.

Operations and the rollback limit

Use scheduled, manual TrueNAS updates, saving configuration first. Run backup jobs after migration, inspect their logs, verify scrub schedules, and send a test alert. SSH-based replication may require recreated connections and tasks after migration; check failures against the preparation notes. For broader security updates, follow our sister publication Tech Sentinel alongside vendor advisories.

Leave Upgrade Pool alone until you commit to the destination: pool feature upgrades are irreversible. CORE-to-SCALE migration is one-way; selecting an old CORE boot environment is not a supported undo. Returning to CORE requires a clean installation and saved configuration, with compatible pool features or a data restore. Keeping the old SSD is useful insurance, not a rollback guarantee.