mismatch firmware on TS-251+ vs drives (do I rollback to earlier firmware, and how?)

English Storage
1

My TS-251+ was on firmware 5.2.4 Build 20250416. Both drives were WD Red 3 Tb.

I wanted to replace the 3 Tb drives with WD Red 8 Tb drives.
I hotswapped a 3 Tb drive with an 8 Tb drive and the RAID rebuild it successfully.

After hotswapping the 2nd 3 Tb drive with an 8 Tb drive the system wouldn’t respond.
I tried to power down the NAS with the front power switch but it wouldn’t so I pulled the power plug and removed all drives.

Upon repowering the NAS it said I needed to initialize the NAS so I updated the firmware to the latest - 5.2.8 Build 20251225 - then powered down. This may have been poor decision.

I reinserted the 1st 8 Tb drive and after the NAS finished booting I received the following error:

Warning 2026-02-12 02:11:55 — — localhost — Firmware Update Firmware Update [Firmware Update] The drive has come from a device with firmware version 5.2.4 Build 20250416 but this device’s firmware version is 5.2.8 Build 20251225. The firmware versions must be the same to use this drive. You can update or re-install this device’s firmware to synchronize the firmware versions of this device and drive.

I was unaware that the firmware and drives had to be synchronized.

From this my thought was to rollback the firmware, insert both 8 Tb drives into the NAS, and update the firmware again.
However, I am unable to find the 5.2.8 Build 20251225 firmware file on the QNAP downloads pages for my NAS model.

Is a rollback the best way to make the drives “accepted” by the NAS?
If so, where do I find the firmware to match what the drives were last built on?
If not, what’re my options?

/Bugsy

2

Most important first question, do you have backups ?

3

yes I have backups.

4

Then start the NAS without drives.

Insert one of the 8TB drives during setup (you need to open the websetup page)

The system will notice that the inserted disk has a QNAP signature and ill offer a non destructive firmware update.
After that is done your NAS should boot up (with a degraded RAID1)
Restore all settings and shared folders (manually pointing them to your cachedev) and then you can clear the second 8TB disk and insert it to rebuild the RAID.

5

We recommend referring to this FAQ article to manually re-install the firmware version 5.2.8.3359 Build 20251225.

Where can I download firmware and update it manually? | QNAP

TS-251+ - Download Center | QNAP