“Disco Dingo” (aka Ubuntu 19.04) is out and available as of today (April 18, 2019). Here’s an update video:
If upgrading, be sure to:
disable all extra (non-ubuntu server) sources in “Software & Updates”
run the normal update process to ensure your existing install is up-to-date
be sure your laptop is either on AC power or at the least has a full 4 hour charge
note: the actual time required for the update from start to finish is between about 75 to 90 minutes. But I like to have some insurance that if there is a hang-up, you have plenty of battery power . . .