Hi,
In the apt-get repositories of ES, if you had a pre-GA version installed and you want to upgrade,
adding the 6.x GA repository and running apt-get update && apt-get dist-upgrade
will not work because 6.0.0
will be listed below 6.0.0-rc2 for example.
$ apt-cache policy elasticsearch
elasticsearch:
Installed: 6.0.0-rc2
Candidate: 6.0.0-rc2
Version table:
*** 6.0.0-rc2 100
100 /var/lib/dpkg/status
6.0.0 500
500 https://artifacts.elastic.co/packages/6.x/apt stable/main amd64 Packages
1.7.3+dfsg-3 500
500 http://azure.archive.ubuntu.com/ubuntu xenial/universe amd64 Packages