Migration from Ubuntu installation to snap

Hello. I have installed version of Rocket Chat 3.1.1 by this instruction docs.rocket.chat/installation/manual-installation/ubuntu
I want to migrate to snap version for simple upgrade rocket chat. Sorry, my knowledge for node and mongo is very poor. I create dump by executing from post Migration from bundle package to snap and try to restore backup by this instruction https://rocket.chat/docs/installation/manual-installation/ubuntu/snaps/#how-do-i-restore-backup-data-to-my-snap, but I have error when restore backup

snap run rocketchat-server.restoredb /var/snap/rocketchat-server/common/backup.tar.gz

  • Your current database WILL BE DROPPED prior to the restore!
  • Do you want to continue?
  1. Yes
  2. No
    #? 1
    [ ] Extracting backup file…
    ls: cannot access ‘/var/snap/rocketchat-server/common/restore/dump/parties’: No such file or directory
    [!] No restore data found within /var/snap/rocketchat-server/common/restore/dump/parties!
    ] Check /var/snap/rocketchat-server/common/restore/restore_20200613.0036.log for details.
    Restore aborted!

And Second, I don’t recieve confirmation email from open.rocket.chat. I look it in spam, but nothing.