Synology: Downgrade from 7.0 DSM Beta

Per Synology website they state you can not downgrade but that isn’t necessary true. Is it as easy as point and click for an upgrade? No, but its not terrible difficult you just need to manually edit a file to fool it s being another version.

Synology Statement

Please read the following before installing this beta software.

  1. For evaluation only – This beta software is for evaluation purposes only and should not be installed in production environments. We strongly recommend reading the Release notes section before the installation. Synology cannot be held responsible for any damage, such as accidental data loss, caused by this beta software.
  2. Not downgradable – After installation, you will not be able to roll back to the previous official version of this software.

For users running the DSM 7.0 Preview Program, the official version of Active insight, Synology Photos, and Secure SignIn apps are now on the app stores. To prevent any compatibility issues, installed Preview version apps must be upgraded via app stores after upgrading to DSM 7.0 Beta.

How to Downgrade

Like many thing sin the IT world what a vendors says and what can be done often differ, such as downgrading DSM. Here are the steps you need to take and it may seem redundant but if you don’t do it this was it will not work. I referenced:

External Reference

  1. Make sure you have telnet client available. If using a Mac you can install using “brew” assuming you have that installed:
# brew install inetutils
  1. Enable Telnet and SSH access
    1. Control Panel -> Click on Advanced Mode (top right)
    2. Now you will see “Terminal & SNMP” Click on it
    3. Click “Enable Telnet Service” -> Apply
  1. Telnet to the 7.0 Beta Synology Diskstation
  2. Make a backup file, more habit because you may not be able to login again?
  3. Overwrite the VERSION file with the new contents
# cat <<EOF> /etc.defaults/VERSION
majorversion="6"
minorversion="2"
productversion="6.2.3"
buildphase="GM"
buildnumber="25426"
smallfixnumber="0"
builddate="2020/05/12"
buildtime="05:59:17"
EOF
# cat /etc.defaults/VERSION
majorversion="6"
minorversion="2"
productversion="6.2.3"
buildphase="GM"
buildnumber="25426"
smallfixnumber="0"
builddate="2020/05/12"
buildtime="05:59:17"
  1. Reboot your Diskstation
  2. Use the Synology Assistant to find the machine and connect to it
  3. Install DSM 6.2.3 using the .pat file downloaded from the Synology Download Center. The upgrade will start but then quickly show an error stating you are unable to downgrade and must install a version of DSM7. Don’t worry, because at this point, Telnet will be available and you will be able to connect to your NAS.
  4. Telnet to your NAS like in step 3, but instead of using your account credentials from before, use the following:
username: root
password: 101-0101
  1. Repeat “Step 5” This is needed because the 7.0 info will be written back out.
  2. Try the Install 6.2.3 again. Your NAS should successfully downgrade to 6.2.3.

Trouble Shooting

DSM Cannot startup normally because …

If you see this after you downgrade:

It only needs the consistency checked, your data still should be there.

  1. Click on Storage Manager
  2. Click on Repair

This will take awhile but should clear the error.

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