Yes, your assumption is correct. On Umbrel OS (especially Raspberry Pi setups), the base OS lives on the microSD card, while all your apps, data, Bitcoin blockchain, files, settings, and configurations are stored on the external SSD. This design allows you to reflash the SD card without losing everything.
When you boot without the SSD, Umbrel detects no external storage and drops you into the fresh setup/restore screen—which is expected behavior.
Recommended Upgrade Path: Clean Flash (Safest for Major Version Jump)
Upgrading from 1.5 to 1.7.1 via the in-UI OTA update has been problematic for many users (especially on Pi 4/5), with failed updates, apps not starting afterward, or other issues.a6989b
Backup first (if not already using Umbrel’s built-in backups):
Use the Backups feature in umbrelOS 1.5 (to USB, NAS, or another Umbrel).
Or manually copy critical data if possible.
Download the latest image:
Get umbrelos-pi4.img.zip from the official releases: Release umbrelOS 1.7.1 · getumbrel/umbrel · GitHub (or the latest).
Flash the new image to your microSD card:
Use Balena Etcher (recommended) or Raspberry Pi Imager.
Flash the .img file to the SD card (not the SSD).
Boot with the SSD attached:
Insert the newly flashed SD card.
Connect your external SSD.
Power on the Pi 4.
It should boot into your existing Umbrel (it detects the data on the SSD and restores/mounts everything). The first boot may take 5–10+ minutes.
Access it:
Go to umbrel.local (or your Pi’s IP) in a browser.
Log in with your existing credentials.
This process is the standard way to “upgrade” the OS on Pi hardware and is more reliable than in-place OTA for bigger jumps.
If OTA Update Still Appeals (Less Recommended Right Now)
In Settings → check for updates and try installing 1.7.1.
Stop all apps first.
Some users report issues with external drives or Mender (the update system)—check logs if it fails (cat /var/lib/mender/device_type, etc.).
Have a backup ready and be prepared to fall back to the flash method.