As you already know, Wireshark is an open-source protocol analyzer software, very used for monitoring the network traffic.
The latest version available is Wireshark 2.6.4 which has been recently released, bringing many changes.
The full list of changes is available here.
Installation instructions:
Up to date packages are available via the Wireshark PPA, so installing the software on Ubuntu should not cause problems to anyone.
All you need to do is add the PPA to your system, update the local repository index and install the wireshark package:
$ sudo add-apt-repository ppa:wireshark-dev/stable
$ sudo apt-get update
$ sudo apt-get install wireshark
Optional, to remove wireshark, do:
$ sudo apt-get remove wireshark
The installation instructions work on Ubuntu 18.04 Bionic Beaver, Ubuntu 16.04 Xenial Xerus and other Ubuntu derivative systems, like Linux Mint and Elementary OS.