How to disable the new UI in JetBrains Rider on a version without this option

If you use IDE Settings Sync plugin to share your IDE settings between machines (ex. home and work), and recently upgraded your Rider up to 2022.2.3 EAP on one of them, and decided to try new UI, then you may experience the issue when this new UI synced to the second machine with the previous Rider version (2022.2). 

The problem is that Rider 2022.2 does not have an option to manage the new UI. And also if you disable this UI in Rider EAP, this will not take any effect for another machine with Rider because of IDEA-304320.

To workaround this issue and switch your Rider 2022.2 back to the classic UI, follow the steps bellow:

1. Open menu “File| Manage IDE Settings | IDE Settings Sync | Choose Settings to Sync
   
2. In the opened dialog set “Disable” for “System Settings” and “Look and Feels” and press “Apply Changes”
   
   

   This option excludes enabling new UI from being synced to JetBrains account.

3. On the second machine restart Rider and check there is a classic UI there. Please be aware that synchronisation may take several minutes and you may not see an effect after the first restart. If this happens, please restart Rider the second time.
   

If the workaround above does not work for you for some reason, you can force it via disabling the registry flag “ide.experimental.ui”:

1. Make sure you have “System Settings” and “Look and Feels” disabled in the settings sync plugin (see step two above).
2. On a machine with Rider 2022.2 open “Help | Find Action” dialog (can be also called by “Shift-Shift” hotkey), and find and open  “Registry…” dialog by typing  “registry” there.
3. In this dialog, find the “ide.experimental.ui” key and disable it.
   
   
4. Restart Rider.