My previous instructions for installing a newer Emacs version on Ubuntu still work. Ubuntu (and in my case, XUbuntu) 19.04 ships with Emacs 26.1 out of the box. As usual I want to run the latest version - Emacs 26.3 - as I run that on my other Linux, FreeBSD and macOS machines.

I only had to make one small change compared to the older instructions. Instead of running the versioned sudo apt-get build-dep emacs25 I ran sudo apt-get build-dep emacs. Once the dependencies are installed, you’re a configure/make/make install away from having a working Emacs 26.3:

timo@timos-thinkpad:~/Downloads/emacs-26.3$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 19.04
Release:	19.04
Codename:	disco
timo@timos-thinkpad:~/Downloads/emacs-26.3$ $HOME/local/bin/emacs --version
GNU Emacs 26.3
Copyright (C) 2019 Free Software Foundation, Inc.
GNU Emacs comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of GNU Emacs
under the terms of the GNU General Public License.
For more information about these matters, see the file named COPYING.

Some of the other instructions on the web mention that there is now a PPA for the latest stable Emacs versions. I’ve not personally used it as I’m comfortable with configuring and building Emacs from the command line. The other advantage with building Emacs from scratch is that it coexists with any other version that you installed from the Ubuntu repositories or other PPAs. This way you can avoid problems like the one described in this askubuntu Stackexchange discussion.