I’m still using the Smartthings Classic app and haven’t received the notification to upgrade. Is there a way to do the upgrade before the notification comes?
You will need a Samsung account in order to use the SmartThings (Samsung Connect) app. So if your SmartThings account has not been migrated yet, you will not be able to use it. You can try contacting ST support to see if they can perform the migration for you. https://support.smartthings.com
And just to be clear, based upon your post’s title, it is your account that will be migrated, not the app. Even if your account is migrated, you can use the old app, the new app or both.