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Tutorial: Downgrade/Rollback from newer version of DSM to older version with Settings preserved


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Since DSM does not allow downgrading if you choose to preserve settings, you need to trick it to believe the installed version is older version



You have updated to newer version 6.2.2 (DSM_DS3615xs_24922.pat) and it is bricked

You want to rollback to 6.2 (DSM_DS3615xs_23739.pat) with setting preserved



Your original USB boot key (For 3615) (USB Drive A)

Any Live Linux USB key (e.g. Debian)  (USB Drive B)

An additional USB boot key (With 3617 loader and corrected VID/PID/MAC, SN is not important )  (USB Drive C)

File: DSM_DS3615xs_23739.pat

File: etc.defaults/VERSION extracted from hda1.tgz from DSM_DS3615xs_23739.pat

File: DSM_DS3617xs_23739.pat

Internet Connection



Part 1: Trick the system that you are running older version

1) Boot with Live Linux (USB Drive B)

2) Install mdadm

3) Mount system partition

4) copy the VERSION extracted earlier and overwrite the one in /etc.defaults/ and /etc/


Part 2: Migrate to 3617

5) Boot using USB Drive C

6) Migrate to 3617 (DSM_DS3617xs_23739.pat). Please choose "preserve setting" during migration


Part 3: Migrate back to 3615

7) Boot using USB Drive A

😎 Migrate back to 3615 (DSM_DS3615xs_23739.pat). Please choose "preserve setting" during migration


Edited by applepie
fix typos
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