Upgrade problem

[Paul Smith]

On Sun, 2019-05-19 at 15:50 -0700, Bob wrote:
> > If there are any errors shown then post it here.
> > Otherwise to upgrade to 19.04 use
> > sudo apt do-release-upgrade
> 
> That command gives the following error message.
> 
> E: Invalid operation do-release-upgrade
> 
> Rebooted the system and tried the command again with the same error message.

The command provided is incorrect; do-release-upgrade is a stand-alone
command, not an apt subcommand.

You want simply:

  sudo do-release-upgrade